a is twice as good a work man as b and together they finish the work in 14 days . in how many days a alone can finish the work ?
"wc = 2 : 1 2 x + x = 1 / 14 = > x = 1 / 42 2 x = 1 / 21 a can do the work in 21 days . answer : b"
inverse(divide(inverse(14), add(const_2, const_1)))