on a certain farm the ratio of horses to cows is 3 : 1 . if the farm were to sell 15 horses and buy 15 cows , the ratio of horses to cows would then be 5 : 3 . after the transaction , how many more horses than cows would the farm own ?
"originally , there were 3 k horses and k cows . 3 ( 3 k - 15 ) = 5 ( k + 15 ) 9 k - 5 k = 75 + 45 4 k = 120 k = 30 the difference between horses and cows is ( 3 k - 15 ) - ( k + 15 ) = 2 k - 30 = 30 the answer is b ."
subtract(subtract(multiply(3, divide(add(multiply(15, 5), multiply(15, 3)), subtract(multiply(3, 3), 5))), 15), add(divide(add(multiply(15, 5), multiply(15, 3)), subtract(multiply(3, 3), 5)), 15))