A started a work and left after working 4 days. B finished the remaining work in next 18 days. If A left the work after working 6 days, then B would have finished the remaining work in 12 days. Find in how many days A and B alone can complete the work.

10, 30

ATQ, If A works for 2 extra day then B finish the work 6 days earlier.

2 days of A's work = 6 days of B's work

Efficiency ratio = A : B = 6 : 2 = 3 : 1

Total work = No. of days × efficiency

                 =  (3 x 4) + (1 x 18) = 30              (according to 1st condition)

A alone will finish the work in = \(\frac{30}{3}\) = 10 days

B alone will finish the work in = \(\frac{30}{1}\) = 30 days