40 workers can complete a work is 15 days. After six days 20 more workers joined them. How many days will they require to complete the remaining work?

Question: 40 workers can complete a work is 15 days. After six days 20 more workers joined them. How many days will they require to complete the remaining work?

Solution:
15 days for the full work
∴ 6 day for = 6/15 = 2/5 of the work

∴ remaining work is = (1 - 2/5) = 3/5
And total workers = 40 + 20 = 60


∴ 40 men can do 1 work in 15 days
∴ 40 men can do 3/5 work in = (15 × 3/5) = 9 days
∴ 60 men can do 3/5 work in = (9 × 40)/60 days
= 6 days