Question

A takes 40 minutes to do a job . B Tajes 1 hour to do same job . A, B and C start doing that job togather. they complete it in only 15 minutes. Had C been alone how much time would he have taken to do that job​

Answer 1

Answer:

Let 1/A = 1/40

and 1/B = 1/60

and 1/A + 1/B + 1/C = 1/15

Add equation 1 and 2

1/A + 1/B = 5 / 120 = 1 /24

Subtract it from equation 3

1/C = 1/24 - 1 /15 = 1 / 40

C = 40 minutes