By what percent will a fraction decrease if its numerator is decreased by 85% and its denominator is decreased by 25%?
Let the original fraction be x / y
After the decreases we have
.15x / .75 y = ( 1/5) (x/y) = .20 (x / y)
So ..... .20(x/y) = (1 -.80) (x/y) = 80% decrease