a can do a piece of work 60 days . b can do work in 20 days . in how many days they will complete the work together ?
"lcm = 60 , ratio = 60 : 20 = 3 : 1 no of days = 60 / ( 3 + 1 ) = 90 / 4 = 15 days answer : c"
divide(const_1, add(divide(const_1, 60), divide(const_1, 20)))