(c) 10 men in 15 days ⇒ 1 man can do the work in 150 days ⇒ 1 man can do twice the work in 300 days Similarly, 18 boys in 15 days ⇒ 1 boy can do the work in 270 days ⇒ 1 boy can do twice the work in 540 days Now, if there are 15 men and 33 boys trying to do twice the work then (15×
1
300
)+(33×
1
540
)=
1
20
+
11
180
=
9+11
180
=
20
180
=
1
9
⇒ It will take 9 days for 15 men and 33 Boys to do twice the work.