Question

5. A can do a piece of work in 40 days. He works at it for 8 days and then B finishes the remaining work in 16 days. How long will they take to complete the work they do it together?​

Answer 1

A can do a piece of work in =40 days
So, A’s 1 day's work =
40
1
​

So, A’s 8 day's work =
40
8
​
=
5
1
​


∴ Remaining work =1−
5
1
​
=
5
4
​


Now, B can do
5
4
​
piece of work in =16 days
So, B’s 1 day's work =
16
(4/5)
​
=
5×16
4
​
=
20
1
​


Therefore, (A+B)’s 1 day's work =
40
1
​
+
20
1
​

=
40
1+2
​
=
40
3
​


∴ Both (A+B) can do a piece of work in =
(3/40)
1
​
days
=
3
40
​
days
=13
3
1
​
days