Respuesta :

 I did some research and found the same problem, I think you stated it wrong:

¹/₂m - ³/₄n = 18
¹/₂m - ³/₄(8) = 18
      ¹/₂m - 6 = 18
             + 6   + 6
            ¹/₂m = 24
       2(¹/₂m) = 2(24)
              m = 48
       (m, n) = (48, 8)
Hope this helped!