Question

A can do a work in 15 days and B in 20 days.
What fraction of the work will be left if they work on it together for 4 days?​

Answer 1

Answer:

take LCM of 15 and 20 as the total amount of work which is 60 units in this case

A can do work on 15 days so work done by A in 1 day=60/15

=4 units

B can do the same amount of work in 20 days so work done by B in 1 day=60/20

=3 units

total work by A and B in a day= 3+4

=7 units

work done in 4days = 7×4

=28

Work left=60-28

=32

Fraction of work left=work left/total work

=32/60

=8/15