a can do a half of certain work in 60 days and b one third of the same in 35 days . they together will do the whole work in .
"a = 120 days b = 105 days 1 / 120 + 1 / 105 = 45 / 2520 = 1 / 56 = > 56 days answer : a"
add(inverse(multiply(60, const_2)), inverse(multiply(35, const_3)))