a can do a job in 30 days and b in 40 days . if they work on it together for 10 days , then the fraction of the work that is left is ?
"a ' s 1 day work = 1 / 30 b ' s 1 day work = 1 / 40 a + b 1 day work = 1 / 30 + 1 / 40 = 7 / 120 a + b 4 days work = 7 / 120 * 10 = 7 / 12 remaining work = 1 - 7 / 12 = 5 / 12 answer is c"
subtract(const_1, multiply(10, add(divide(const_1, 30), divide(const_1, 40))))