a is half good a work man as b and together they finish a job in 20 days . in how many days working alone b finish the job ?
"wc = 1 : 2 2 x + x = 1 / 20 = > x = 1 / 60 2 x = 1 / 60 = > 30 days answer : b"
multiply(20, divide(const_3, const_2))