# Ok, one more...solve the given formula for the variable?

##### New member
P=4s : Solve for s.
Is this how I do it? s=P-4? Or is that completely wrong? I'm all new to literal equations and formulas.

Here's some harder ones:

C=5/9(F-32) Solve for F
A=1/2(b^1+b^2)h Solve for h

And one other, and I'm done...for now. :? Don't worry, though, I'll be back. But...in solving for y, which is pretty easy, how do I do it in a problem that involves fractions, such as:

3/4x - 2/5y = 1/2

I don't see how I could multiply by a common denominator, as in equations with a single variable. Do I multiply by reciprocals? I need an explanation on that, too.

Thanks, again! I appreciate all your help!

#### Subhotosh Khan

##### Super Moderator
Staff member
P=4s : Solve for s.
Is this how I do it? s=P-4? Or is that completely wrong? I'm all new to literal equations and formulas.

Here's some harder ones:

C=5/9(F-32) Solve for F
A=1/2(b^1+b^2)h Solve for h

And one other, and I'm done...for now. :? Don't worry, though, I'll be back. But...in solving for y, which is pretty easy, how do I do it in a problem that involves fractions, such as:

3/4x - 2/5y = 1/2

I don't see how I could multiply by a common denominator, as in equations with a single variable. Do I multiply by reciprocals? I need an explanation on that, too.

Thanks, again! I appreciate all your help!

http://www.purplemath.com/modules/solvelin.htm

As for the first problem

P = 4s means

P is equal to 4
multiplied by s

So the next step in solution is "isolation" - for that you have to do "opposite" operation (inverse operation). Inverse of multiplication is division.

Since 's' is multiplied by 4 - to isolate 's' you need to divide by '4'.

p = 4 * s

p/4 = 4*s/4

p/4 = s

You really need a face-to-face tutor to have these explained properly.

#### stapel

##### Super Moderator
Staff member
Note: Not all of the posters here are young, with sharp eyesight. In particular, many tutors are older, and some of us have astonishingly-bad vision. It might be helpful to be considerate of those needs, and post in a font color that is less faint than is olive; if this color choice is necessary for some reason, then perhaps the text could be bolded...?

Eliz.

better colors: darkred, orange, brown, green, darkblue, indigo, black

colors good for highlighting: red, blue

colors better avoided for text: violet, white (white), yellow, olive, cyan

##### New member
stapel said:
Note: Not all of the posters here are young, with sharp eyesight. In particular, many tutors are older, and some of us have astonishingly-bad vision. It might be helpful to be considerate of those needs, and post in a font color that is less faint than is olive; if this color choice is necessary for some reason, then perhaps the text could be bolded...?

Eliz.

better colors: darkred, orange, brown, green, darkblue, indigo, black

colors good for highlighting: red, blue

colors better avoided for text: violet, white (white), yellow, olive, cyan
Oh dear. I'm sorry, I should have thought of that. I will remember to do that. Thanks for the notification!

#### stapel

##### Super Moderator
Staff member
Oh dear. I'm sorry, I should have thought of that. I will remember to do that. Thanks for the notification!
Not a problem! I sometimes forget that my vision isn't the norm, either -- until my snotty little (sharp-eyed) ten-year-old boy sees things that I can't make out. :wink:

On the other hand, he's color-blind, so I've got 'im there. :lol:

Eliz.

##### New member
stapel said:
Oh dear. I'm sorry, I should have thought of that. I will remember to do that. Thanks for the notification!
Not a problem! I sometimes forget that my vision isn't the norm, either -- until my snotty little (sharp-eyed) ten-year-old boy sees things that I can't make out. :wink:

On the other hand, he's color-blind, so I've got 'im there. :lol:

Eliz.
That's funny! I have a two year old brother and 6 month old sister, and that little two year old spots out some things (especially bugs and "ANTS!") So I know what you're talking about!

Back on the math topic: I solved the problems I was having with literal equations (not linear) by simply studying the subject for a half hour till it clicked. :idea: But may I ask you math experts, is my reasoning correct in the following problem?

Celsius equals 5/9(Fahrenheit-32) or C=5/9(F-32). Solve for Fahrenheit.
Multiply both sides by 9/5 = C(5/9)=F-32
C(5/9) + 32 = F

Is that correct? Do I keep the parenthesis as they are in the final answer?

And, in P = a+b+c, solving for b brings me to P-a-c=b. Do I subtract a and c? I can't inverse it to division because no muliplication is on the right side. But did I do it ok?

Thanks a lot, again!

#### wjm11

##### Senior Member
Celsius equals 5/9(Fahrenheit-32) or C=5/9(F-32). Solve for Fahrenheit.
Multiply both sides by 9/5 = C(5/9)=F-32
C(5/9) + 32 = F

Is that correct? Do I keep the parenthesis as they are in the final answer?

And, in P = a+b+c, solving for b brings me to P-a-c=b. Do I subtract a and c? I can't inverse it to division because no muliplication is on the right side. But did I do it ok?
Almost right! You’re thinking is correct, but you have a typo: You said multiply [both sides] by 9/5, but then you wrote C(5/9). It should be C(9/5). Final equation is

C(9/5) + 32 = F

PS Blue-green color blindness in males is a trait passed on by the mother (from her X chromosome) to male offspring, I believe.

For the second question, you are correct: Subtract both “a” and “c” from both sides of the equation.

##### New member
wjm11 said:
Celsius equals 5/9(Fahrenheit-32) or C=5/9(F-32). Solve for Fahrenheit.
Multiply both sides by 9/5 = C(5/9)=F-32
C(5/9) + 32 = F

Is that correct? Do I keep the parenthesis as they are in the final answer?

And, in P = a+b+c, solving for b brings me to P-a-c=b. Do I subtract a and c? I can't inverse it to division because no muliplication is on the right side. But did I do it ok?
Almost right! You’re thinking is correct, but you have a typo: You said multiply [both sides] by 9/5, but then you wrote C(5/9). It should be C(9/5). Final equation is

C(9/5) + 32 = F

PS Blue-green color blindness in males is a trait passed on by the mother (from her X chromosome) to male offspring, I believe.

For the second question, you are correct: Subtract both “a” and “c” from both sides of the equation.
Woot, woops! There I go again with my typos. My fault! Sorry! I did that in class the other day...the professor said, Why'd you write x>=-2 on the answer, and shade in -1 on the graph line? Did I EVER feel dumb. And I'm not old, either, so I have no excuse. :roll:

OT: Yes, I remember learning the chromosomes in biology last year. I liked biology, it was so much fun. Especially describing an atom and how blood circulates through the heart, passing through the arteries into the lymphatic system, which is composed of nodes and nodules....I could go on for hours, but everyone says they're bored when I say that! I can't understand it! :?:

Back on the math topic: Thanks again for your help!