Alejandro and Pedro are riding their bike to school. After 1 mile, the are 5/8 of the way there. How much farther do they have to go?

The correct answer is 3/5th of a mile

1 / (5/8) = x / 1 ... 1 mile to 5/8 = x miles to 1

cross multiply

5/8x = 1

x = 1 / (5/8)

x = 1 * 8/5

x = 8/5 or 1 3/5 miles ... total distance

and if they already rode 1 mile ... (1 3/5 - 1) = 3/5 of a mile left to go <==