When we add
up the given rates, we get 1/5, which is the rate that 2 Ahmads, 2 Kumars and
2 Calvins would work. Unfortunately we
do not have the clones. We just have one
Ahmad, one Kuman and one Calvin. So we
divide that by 2 to get 1/10 and this is their combined rate. This means that they can complete 1
house in 10 days.