a can finish a piece of work in 12 days . b can do it in 20 days . they work together for 9 days and then a goes away . in how many days will b finish the work ?
"9 / 12 + ( 9 + x ) / 20 = 1 = > x = 5 days answer : c"
divide(subtract(const_1, add(multiply(divide(const_1, 12), const_2), multiply(divide(const_1, 20), const_2))), divide(const_1, 20))