Painter 'A' can paint a house in 50 days and 'B' can do it in 25 days. With help of 'C', they did the job in 10 days only. Then, 'C' alone can do the job in

Let total work to be done = 100 units

Painter 'A' can paint a house in 50 days and 'B' can do it in 25 days

=> A's efficiency = $$\frac{100}{50} = 2$$ units/day

B's efficiency = $$\frac{100}{25} = 4$$ units/day

Let C's efficiency = $$x$$ units/day

According to ques, all of them complete the job in 10 days

=> $$(2+4+x) \times 10 = 100$$

=> $$x+6=\frac{100}{10}=10$$

=> $$x=10-6=4$$

$$\therefore$$ Time taken by C alone to do the job = $$\frac{100}{4}=25$$ days

=> Ans - (C)