a can finish a piece of work in 5 days . b can do it in 15 days . they work together for two days and then a goes away . in how many days will b finish the work ?
"2 / 5 + ( 2 + x ) / 15 = 1 = > x = 7 days answer : e"
divide(subtract(const_1, add(multiply(divide(const_1, 5), const_2), multiply(divide(const_1, 15), const_2))), divide(const_1, 15))