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Category: Math
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Experience:  B.S. in Civil Engineering
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My son is doing his GCSE maths. While I can come up with the

Customer Question

My son is doing his GCSE maths. While I can come up with the answer to most of the questions he struggles with, I do not know how to show my work, or what is expected by whomever is marking the question. This is the question... Sally has 4 times as many GPB's as Ted. If she gives £3 away she will have 2 times as many GBP's as Ted. How many £'s would Sally be left with?
Submitted: 4 years ago.
Category: Math
Expert:  Ryan replied 4 years ago.

Hi,

Thank you for using the site. I'll have a solution posted for you shortly.

Ryan

Expert:  Ryan replied 4 years ago.

One way to approach this problem is with simultaneous equations.

Let x represent the number of GPBs that Sally currently has, and let y represent the number that Ted currently has.

Since Sally currently has 4 times as many as Ted, you can write the following equation:

x = 4y

After Sally gives away 3, she will have x - 3 left, and this will then be equal to 2 times the number that Ted has. From this you can write a second equation:

x - 3 = 2y

From the first equation we know that x is equal to 4y, so we can substitute 4y in place of x in the second equation, which gives:

4y - 3 = 2y

This can be rearranged as:

4y - 2y = 3

2y = 3

y = 3/2 = 1.5

So Ted currently has 1.5 GPBs.

Since Sally currently has 4 times as many as Ted, she has started with 4(1.5) = 6 GPBs.

After she gives away 3, she will have 6 - 3 = 3 GPBs left. 