Question

A and B separately do a work in 10 and 15 days respectively.They worked together for some days and then A completed the remaining work in 5 days .For how many days did had A and B worked together?

Answer 1

let A & B worked together for x days
work done by A in 1 day=1/10
by B in 1 day =1/15
work done together in 1 day=1/10+1/15=5/30=1/6
work done together in x days=x/6
remaining work=1-x/6
1-x/6=5/10=1/2
x/6=1/2
x=3 days

Answer 2

Answer:

A and B together can do a work in 3 days