a can do a piece of work in 7 days and b can do it in 6 days how long will they both work together to complete the work ?
"explanation : a ’ s one day work = 1 / 5 b ’ s one day work = 1 / 6 ( a + b ) ’ s one day work = 1 / 7 + 1 / 6 = 13 / 42 = > time = 42 / 13 = 3 3 / 13 days answer : option c"
divide(const_1, add(divide(const_1, 7), divide(const_1, 6)))