Test 4 Section 9 - #1 (page 609)

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.


  1. Is there an algebraic way to solve it?

  2. Of 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!)

    b = g
    2(b - 4) = g

    Solve for g.