Question

the time it takes to lay a sidewalk of a certain type varies directly as the length and inversely as the # of men working. If eight men take 2 days to lay 100 ft, how long will it take 3 men to lay 150 ft??

Answer 1

If 8 men ----------------------------- >take 2 days to lay 100 feet

then
they can lay 50 feet in a day.
Each man lays 50/8 or 6.25 feet per day. 

3 men can lay 3 * 6.25 = 18.75 feet per day. 

150/18.75 = 17.14 days. 

the answer is 17.14 days.