A alone can do a work in 12 days while A and B together can do that work in 7.5 days. Find the time taken by C alone to do that work if C takes 3 days more than that of B alone to do that work?

Let total work be 60 units (LCM of 12 and 7.5)

Efficiency of A= 5 units/ day

Efficiency of A and B together= 8 units/ day

Efficiency of B= 3 units/ day

Time taken by B alone to do that work=20 days

Time taken by C alone=23 days