Question

A takes 10 days less than the time taken by b to finish a piece of work. If both a and b can do it in 12 days, then the time taken by b alone to finish the work is

Answer 1

let B takes x days and A takes x-10 days
when both A and B work together, work done in 1 day is (1/x) + (1/(x-10)) = (2x-10)/(x^2 - 10x)
Total days in which work is completed when both A and B work together are (x^2 -10x)/(2x-10) = 12
=> x^2 -34x +120 =0
x = 30 days