Strategy Guide 2: FDP page 127, question 10

[c_o_]

Can someone please explain how they solved this problem:

A water drum is filled to 1/4 of its capacity. If another 30 gallons of water were added, the drum would be filled. How many gallons of water does the drum currently contain?

Thanks!

[tommywallach]

So 30 = 3/4 capacity.

30 = 3/4x

x = 40

Capacity is 40, so currently the drum has 10 (as we know it would be filled if you added 30).

That is the full solution. Was there confusion there?

-t