mala and usha shared their water from a bottle . if mala and usha both drank for the same amount of time , but usha only drank 2 / 10 of the total bottle , what was the ratio of mala and usha speed ?
the answer is suppose to be c . 4 : 1 . it ' s from the gmatprep answer : option c
divide(subtract(10, 2), 2)