a is half good a work man as b and together they finish a job in 12 days . in how many days working alone b finish the job ?
"c 18 wc = 1 : 2 2 x + x = 1 / 12 = > x = 1 / 36 2 x = 1 / 18 = > 18 days"
multiply(12, divide(const_3, const_2))