Question

A and B together can complete a piece of work in 15 days. They started

working together but after 11 days, A left. The rest of the work is completed

by B in 12 days. In how many days can A alone do the whole work?​

Answer 1

Step-by-step explanation:

a and b can complete the work in 15 days.

Percentage of work done by a and b in one day = 100/15=6.66%

b alone can complete the whole work in 20 days.

So, percentage of work done by b in one day = 100/20=5%

Percentage of work done by a in one day = 6.66-5=1.66%

Thus, a can complete the whole work alone in = 100/1.66=60 days (approx)

Alternatively,

a and b can complete the work in = 15 days

Part of work done by a and b in one day= 1/15

b can complete the work alone in = 20 days.

so, part of work done by b in one day = 1/20

Part of work done by a = 1/15 - 1/20= 1/60

a can complete the work in = 1/(1/60) = 60 days.

C

Answer 2

Answer:

A and B complete work together in 15 days

Step-by-step explanation:

B alone completed in 12 days , so that's why

= 15×12÷15-12

=180÷3

=60

A alone do the whole work in 60 days

I think this is the most simple way to solve this question and you find this helpful