a man can do a piece of work in 6 days , but with the help of his son , he can finish it in 3 days . in what time can the son do it alone ?
"son ' s 1 day work = 1 / 3 - 1 / 6 = 1 / 6 son alone can do the work in 6 days = 6 days answer is d"
divide(multiply(6, 3), subtract(6, 3))