Worded maths problem, equations.

[whoopdido2u2]

Hi, first post, could someone please explain to me how I would go about solving this problem as I cannot seem to remember;

Claire, Leanne and Lindsay are sisters. Claire is 2 years older than Leanne and Leanne is 4 years older than Lindsay. The sum of all their ages is 54. How old is each sister?

Help is very much appreciated thanks!

 

[JeffM]

Hi, first post, could someone please explain to me how I would go about solving this problem as I cannot seem to remember;

Claire, Leanne and Lindsay are sisters. Eclair is 2 years older than Leanne and Leanne is 4 years older than Lindsay. The sum of all their ages is 54. How old is each sister?

Help is very much appreciated thanks!

Here is the deal. First, thank you for giving a clear statement of the problem. Second, read the thread entitled Read Before Posting. Third, let us know where you are in your schooling, what you are studying (you posted this under Arithmetic but it looks more like a problem in beginning algebra), and what you have done on this problem so far. If you have tried to solve it, please show us your work so we can see where you have got stuck or where you have gone wrong. If you do not know where to start, tell us what you have thought about trying. This is a HELP site, not an ANSWER site.

 

[whoopdido2u2]

Here is the deal. First, thank you for giving a clear statement of the problem. Second, read the thread entitled Read Before Posting. Third, let us know where you are in your schooling, what you are studying (you posted this under Arithmetic but it looks more like a problem in beginning algebra), and what you have done on this problem so far. If you have tried to solve it, please show us your work so we can see where you have got stuck or where you have gone wrong. If you do not know where to start, tell us what you have thought about trying. This is a HELP site, not an ANSWER site.

I understand what you mean, I'm in year 10 here in Australia studying "equations and inequalities", I have already done problems like these a couple years ago but I can't seem to remember how to do them (I'm sure it's something extremely simple).

What I've done http://pbrd.co/YcRXAm (sorry about the clarity)

 

[HallsofIvy]

Hi, first post, could someone please explain to me how I would go about solving this problem as I cannot seem to remember;

Claire, Leanne and Lindsay are sisters.

Okay, let x, y, and z be the ages of Claire, Leanne, and Lindsay, respectively.

Claire is 2 years older than Leanne

x= y+ 2

and Leanne is 4 years older than Lindsay.

y= z+ 4

The sum of all their ages is 54. How old is each sister?

x+ y+ z= 54

Help is very much appreciated thanks!

You now have three equations to solve for x, y, and z.

 

[JeffM]

Do you remember how to solve simultaneous linear equations? By the way, the first thing to do in any word problem is to assign a unique letter to each relevant unknown in writing. The writing takes one burden off your memory and let's you communicate easily about your problem. The second thing to do is to translate each piece of information given in the problem in words into equations or inequations using the letters that you assigned. Do that in writing too so you can see the information in mathematical form. Do you see that I have just given you a general description of what Halls did specifically for this problem? You will find word problems MUCH easier if you make this a habit. It may also give you partial credit on a test even if you make a mistake somewhere along the way.

 

[whoopdido2u2]

Do you remember how to solve simultaneous linear equations? By the way, the first thing to do in any word problem is to assign a unique letter to each relevant unknown in writing. The writing takes one burden off your memory and let's you communicate easily about your problem. The second thing to do is to translate each piece of information given in the problem in words into equations or inequations using the letters that you assigned. Do that in writing too so you can see the information in mathematical form. Do you see that I have just given you a general description of what Halls did specifically for this problem? You will find word problems MUCH easier if you make this a habit. It may also give you partial credit on a test even if you make a mistake somewhere along the way.

Jesus, I read the words "simultaneous equations" and it all came back to me, how could I be so stupid... we actually haven't started them in class yet so I don't know why we've been given these questions. I've already done the question, but I'm just curious, would there have been another way of solving it?

 

[JeffM]

Jesus, I read the words "simultaneous equations" and it all came back to me, how could I be so stupid... we actually haven't started them in class yet so I don't know why we've been given these questions. I've already done the question, but I'm just curious, would there have been another way of solving it?

Trial and error (or as they seem to call it nowadays, guess and check). You can grow old solving problems that way. The whole point of algebra is to let you solve this sort of problem efficiently.

 

[HallsofIvy]

Hi, first post, could someone please explain to me how I would go about solving this problem as I cannot seem to remember;]

Well, you never HAVE to use "simultaneous equations"- that just makes the individual equations simpler. Since I did not know you had not covered "simultaneous equations", I gave it the way I would set it up.

Claire, Leanne and Lindsay are sisters. Claire is 2 years older than Leanne

So let "x" be Leannes' age. Then Clair's age is x+ 2.

and Leanne is 4 years older than Lindsay.

And Lindsay's age is x- 4. (I may have reversed these before.)

The sum of all their ages is 54.

So x+ (x+ 2)+ (x- 4)= 54

How old is each sister?

Help is very much appreciated thanks!

Solve that equation for x (Leanne's age) and find Claire and Lindsay's age from that.