worker a takes 5 hours to do a job . worker b takes 15 hours to do the same job . how long it take both a & b , working together but independently , to do the same job ?
"one day work of a = 1 / 5 one day work of b = 1 / 15 so one day work of a and b together = 1 / 5 + 1 / 15 = 4 / 15 so total days required = 15 / 4 answer : a"
divide(const_1, add(divide(const_1, 5), divide(const_1, 15)))