Question

Andy and bill together can paint a room in 10 days. Andy alone can complete it in 18 days. If bill paints the room only for half a day daily, then in how many days will andy and bill together compute the work?

Answer 1

let bill do work =x days
( Andy +bill ) do work = 10days
hence,
18x/(18+x)=10

18x=180+10x
8x=180
x =45/2 days
hence bill do work =45/2 days
again questions say ,bill capacity now half then do work =45 days

now when they work together ,
=18 x 45/(18+45)=90/7 days