a and b together can do a work in 3 days . if a alone can do it in 6 days . in how many days can b alone do it ?
"1 / 3 – 1 / 6 = 1 / 6 = > 6 answer : e"
add(inverse(subtract(divide(const_1, 3), divide(const_1, 6))), divide(const_2, add(const_2, const_3)))