Question

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

Answer 1

a--10:b--15-----work=lcm of both two is 30
so a can do 3 per day
so b can do 2 per day
(a+b)---+a(5d*3)=30=>a+b=15
there fore 15/5( both work 2+3)=3 days