if a , b and c together can finish a piece of work in 4 days . a alone in 36 days and b in 18 days , then c alone can do it in ?
"c = 1 / 4 - 1 / 36 – 1 / 18 = 1 / 6 = > 6 days ' answer : e"
divide(const_1, subtract(subtract(const_0_25, divide(const_1, 36)), divide(const_1, 18)))