A can do a piece of work in 20 days and B in 30 days. They work together for 5 days. How much work is left?
Show answer & explanation
Correct answer: C
Explanation
Given:
A completes the work in = 20 days
B completes the work in = 30 days
Both work together for = 5 days
According to the formula:
Work done in 1 day = 1 / Total days
A's work in 1 day = 1/20
B's work in 1 day = 1/30
(A + B)'s work in 1 day = 1/20 + 1/30
= (3 + 2) / 60 = 1/12
Work done in 5 days = 5 × 1/12 = 5/12
Remaining work = 1 − 5/12 = 7/12