A and B together can do 8/15 of a work in 5 days and B alone can do the remaining work in 7 days. Find in how many days A alone can do the work?

Correct option is B

Remaining work = 1-8/15=7/15
So, B alone can do 7/15 th of work = 7 days
B alone can do the whole work = 15/7×7=15 days
Both together can do the whole work = 15/8×5=75/8 days
Total work = 75 unit
Efficiency of B = 75/15=5 unit/day
Efficiency of A = 8 –5 = 3 unit/hour
Required days = 75/3 = 25 days