Lesson: Summarizing Information

Comment on Summarizing Information

i found the videos very useful.

yeah, great effort and explanation ;)

Really good and easy to understand!

Can you please explain how the both answer choices are sufficient for the question (of the 27 children...how many are boy?) I thought that both answers were insufficient because they did not provide any exact number.
gmat-admin's picture

Once we have two different linear equations with 2 variables, we can solve that system for the two variables. In other words, we can find the exact values of B and G.

This is covered in these two videos:
- https://www.gmatprepnow.com/module/gmat-algebra-and-equation-solving/vid...
- https://www.gmatprepnow.com/module/gmat-algebra-and-equation-solving/vid...

Let's take the first statement where we have:
B = 2G
B + G = 27

Since B = 2G, we can take the second equation B + G = 27, and replace B with 2G.
We get: 2G + G = 27
Simplify: 3G = 27
Solve: G = 9

Once we know that G = 9, we can take one of our equations (e.g., B = 2G) and replace G with 9.

We get: B = 2(9) = 18

So, G = 9 and B = 18
In other words, there are 18 boys.

Does that help?

Cheers,
Brent

It makes sense now, thank you!

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