Question

'A' can do half of the work in 10 days. After B joins, both worked for 5 days. B left and the remaining work was completed by A in 4 days. In how many days can B alone do the work?

Answer 1

total work done is always equal to 1
so let B worked for x days then
B 1 day work -------->1/x
similarly, A 1 day work---------->1/20
now,