a can do a piece of work in 4 days . b can do it in 5 days . with the assistance of c they completed the work in 2 days . find in how many days can c alone do it ?
"c = 1 / 2 - 1 / 4 - 1 / 5 = 1 / 20 = > 20 days answer : b"
divide(multiply(4, 5), divide(subtract(multiply(4, 5), multiply(add(divide(multiply(4, 5), 4), divide(multiply(4, 5), 5)), 2)), 2))