a can do a job in 8 days and b can do it in 20 days . a and b working together will finish twice the amount of work in - - - - - - - days ?
"explanation : 1 / 8 + 1 / 20 = 7 / 40 40 / 7 = 40 / 7 * 2 = 11 3 / 7 days answer : b"
add(divide(const_1, 8), divide(const_1, 20))