Question

A and b can do a work in 12 days and 24 days respectively.they worked together for 4:days but after 4 days b left.how long willit be taken by a to completevthe renaining work

Answer 1

Work by A in 1 day = 1/20

Work by B in 1 day = 1/12

Together they work = (1/20)+(1/12) = (3 + 5)/60 = 8/60 = 2/15

Total time taken by them = 7.5 days

But here A work 5 days alone.

Work by A in 5 days = (3/60)×5 = 15/60

Let x be the number of days they work after.

After that they work together,

(15 + × (3+8))/60 = 1

8x = 60 - 15

x = 45/8

x = 5(5/8) days

Total time taken = 5 + 5 (5/8) = 10 (5/8)days