Let t be the time (in hours) he spent running. Then the time he swam was (7.5 - t) hours. The total distance equation then is 9*t+ 2*(7.5-t) = 46.5 9t + 15 - 2t = 46.5 7t = 46.5 - 15 = 31.5 t == 4.5. Answer. He ran for 4.5 hours and swam for 7.5-4.5 = 3 hours. Check. 9*4.5 + 2*3 = 46.5 kilometers. ! Correct !