Question

A gardener can care for the Green's property in 5 hours. If his helper assists him, they can complete the job in 4 hours. How long will it take the helper to do the job?

Answer 1

20 HOURS

Explanation:

Both the gardener and the helper take 4 hours which means that working together they complete 1/4 of the job.

The gardener alone takes 5 hours meaning that he completes 1/5 of the job in 1 hour.

then, to get the portion done by the helper in 1 hour we subtract fraction done by the gardener in 1hr from the fraction done by both in the same time.

1/4-1/5=1/20

to get the time the helper takes we find the reciprocal of 1/20 which is 20 HOURS