A is thrice as good a work man as B and takes 10 days less to do a piece of work than B takes. B can do the work in:___________?

B. 14 days
C. 16 days
D. 30 days

Raio of times taken by A and B = 1 : 3
If the difference of time is 2 days, B takes 3 days. If the difference of time is 10 days.
B takes [3/2×10]=15 days