one fast typist type some matter in 4 hrs and another slow typist type the same matter in 6 hrs . if both do combine in how much time they will take to finish .
"fast ' s 1 hr work = 1 / 4 slow ' s 1 hr work = 1 / 6 1 / 4 + 1 / 6 = 5 / 12 they ll finish in 12 / 5 hrs = 2 2 / 5 = = > 2 hr 24 mins answer : c"
multiply(divide(const_1, add(divide(const_1, 4), divide(const_1, 6))), const_10)