a works twice as fast as b . if b can complete a work in 12 days independently , the number of days in which a and b can together finish the work in :
"explanation : ratio of rates of working of a and b = 2 : 1 . so , ratio of times taken = 1 : 2 . b ' s 1 day ' s work = 1 / 12 a ' s 1 day ' s work = 1 / 6 ; ( 2 times of b ' s work ) ( a + b ) ' s 1 day ' s work = ( 1 / 6 + 1 / 12 ) = 3 / 12 = 1 / 4 so , a and b together can finish the work in 4 days . answer is a"
inverse(add(divide(const_1, 12), multiply(const_2, divide(const_1, 12))))