Please can some help with worded Simulataneous Equations

Otis

Senior Member
We just cross-posted, so I didn't see your latest images until now. Thank you for posting them.

Your work using the substitution method looks great. Some of your divisions were done in two steps (instead of one step), but you arrived at the correct values for A and B. (The exercise told you to use symbols x and y, but they're only names, so that's not a big deal.)

30A = 36

You tried to solve for A by subtracting 30 from each side. You need to divide by 30 (instead of subtracting) because 30 and A are multiplied together.

IF the left-hand side of the equation were 30 + A, instead, then you would subtract the 30.

Remember:
Subtraction undoes addition: (x + 5) Subtract 5, to get rid of it.
Addition undoes subtraction: (x - 2) Add 2, to get rid of it.
Division undoes multiplication: (7x) Divide by 7, to get rid of it.
Multiplication undoes division: (x/3) Multiply by 3, to get rid of it.

Good work! Cheers

mazph

New member
Sorry about the Elimination part, did you see my workings above.thank you again.

mazph

New member
Thank you so much I now understand. Will redo all questions later just to embed the method.

Subhotosh Khan

Super Moderator
Staff member
Here's an example exercise.

Denis bought 62 pencils. ....

I hope this example helps you to write two equations and to find the solution, for problem #6. Cheers

Are you trying to make an example out of Denis??

Otis

Senior Member
Are you trying to make an example out of Denis??
Not intentionally. But, Denis once showed me expensive pencils he used at work, doing books for high-end clientele, so I thought a real-world example would be nice. (For Jomo, he uses cruddy pencils from Office Depot.)

Otis

Senior Member
Thank you so much I now understand …
You're welcome.

I just noticed something with the equation 30A = 36 (mentioned in post #21). That ought to be 0.30A = 36, but, perhaps you know that. (I'm thinking that you divide by decimal numbers differently than I do.)

Cheers

mazph

New member
you are right , don't know why I did it the other way.

thank you.

Jomo

Elite Member
Not intentionally. But, Denis once showed me expensive pencils he used at work, doing books for high-end clientele, so I thought a real-world example would be nice. (For Jomo, he uses cruddy pencils from Office Depot.)

Gee thanks Otis. I will never forget your kind thought.

Jomo

Elite Member
Not intentionally. But, Denis once showed me expensive pencils he used at work, doing books for high-end clientele, so I thought a real-world example would be nice. (For Jomo, he uses cruddy pencils from Office Depot.)

I even have a 25% off coupon so I get them for 4 cents each instead of 5 cents. I only buy one at a time because if I buy two they charge me sales tax. I save 8 cents of tax for 25 pencils! The cashiers love when they see me come in.

ksdhart2

Senior Member
I even have a 25% off coupon so I get them for 4 cents each instead of 5 cents. I only buy one at a time because if I buy two they charge me sales tax. I save 8 cents of tax for 25 pencils! The cashiers love when they see me come in.
I have a similar elaborate system whereby I visit (at least) three different gas stations every time I fill up my car. It's time consuming but worth it. Why, just this month, I've saved \$2.43!