(1) Let the time taken by Anu and Bobby be x days and y days respectively Since Bobby is 25% more efficient than Charu, therefore time taken by Charu =
5y
4
days According to question,
1
y
+
4
5y
=
3
40
⇒ y = 24 Therefore, time taken by Charu =
5×24
4
=30days and
1
x
+
1
24
=
7
72
⇒x=18 Therefore, work done by Anu and Charu together in 1 day =