You can backsolve this one. Start with (C): If there are 8 girls on the bus, that means that there were 8 boys on the bus to start as well.

At the first stop, 4 boys got off and nobody got on, so now there are 4 boys on the bus and still 8 girls.

That's twice as many girls as there are boys (just like the question says) so (C) is our answer.

## 5/17/11

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Is there an algebraic way to solve it?

ReplyDeleteOf course! (Although the whole purpose of a technique like backsolve is that you have something else you can try when you don't see the algebra!)

ReplyDeleteb = g

2(b - 4) = g

Solve for g.