Question

The water in a reservoir decreased by 47% during a drought. Before the drought, the reservoir held 44,580 acre ft (AF) of water.

Answer 1

44,580 x 47 %

44,580 x .47 = 20,952.6

So, the water decreased 20,952.6 ft

If you want the water level after the drought just subtract.

44,580 - 20,952.6 =  23,627.4 ft

Hope this helps. :)