By what percent will the product of two numbers decrease if one of them is decreased by 25% and the other is decreased by 50%?
original numbers: x and y
original product : xy
new numbers: .75x and .5y
new product = .375xy or (3/8)xy
change in product = (5/8)xy
percentage change = (5/8)xy/(xy)
= 5/8
= .625
= 62.5 %