a and b can do a piece of work in 10 days , b and c in 5 days , c and a in 15 days . how long will c take to do it ?
2 c = 1 / 5 + 1 / 15 – 1 / 10 = 1 / 6 c = 1 / 12 = > 12 days answer : c
divide(multiply(10, const_3), subtract(divide(add(divide(multiply(10, const_3), 15), add(divide(multiply(10, const_3), 10), divide(multiply(10, const_3), 5))), const_2), divide(multiply(10, const_3), 10)))