Question

3.
A can do a work in 15 days and B in 20 days. If they work on it together for 4 days, then the
fraction of the work that is left is:
a. 1/4
b. 1/10
c. 7/15
d. 8/15

Answer 1

d )= 8 / 15

HOPE ITS HELP YOU

Answer 2

Amount of work A can do in 1 day = 1 / 15

Amount of work B can do in 1 day = 1/20

Amount of work done by A and B in 1 day = 1 /15 + 1/20

1 / 15 + 1 /20 = 7 / 60

Amount of work A and B can together do in 4 days =

4 ✖ 7 / 60 = 7 / 15

Fraction of work left = 1 - 7 / 15 = 8 /15

option d is correct

Hope it is helpful