A alone can do a work in 20 days. A and B together can do the same work in 15 days. B and C together can do the same work in $\frac{75}{2}$ days. What is the ratio of the efficiency of A, B and in terms of doing the work?

15 : 5 : 3

A = 20 days,

A + B = 15 days,

B + C = \(\frac{75}{2}\) days,

⇒ A + B = 20 

⇒ 15 + B = 20

⇒ B = 5,

Similarly,

⇒ B + C = 8

⇒ 5 + C = 8

⇒ C = 3,

Therefore efficiency ratio is,

 A : B : C = 15 : 5 : 3