Question

Takes 3/4 of an hour to cut 3/5 of the lawn. How long will it take to cut the whole lawn?

Answer 1

the whole lawn is 1/(3/5) = 5/3 as much as he can cut in 3/4 of an hour

5/3 * 3/4 = 5/4

or, keeping track of the units,

(1 lawn) * (3/4 hr)/(3/5 lawn) = 3/4 * 5/3 = 5/4 hr

Answer 2

(3/4)/(3/5) = x/1.
3/4*5/3 = x/1,
X = 5/4 h.