SSC MTS 2 Aug 2019 Shift 3 Paper

Short Trick:

A and B together one day work will be 29 units.
3 day work is 3 × 29
∴ The work which is completed = (3 × 29)/168 ⇒ 29/56
Detailed Solution :
A can do a piece of work alone = 8 days
⇒ A can do a piece of work in 1 day = 1/8
⇒ A can do a piece of work in 3 day = 3/8
⇒ B can do a piece of work alone = 21 days
⇒ B can do a piece of work in 3 days = 3/21
⇒ They work together for 3 days = 3/8 + 3/21 = 87/168 = 29/56
∴ Complete part in 3 days is 29/56.