因为 x = 1/2 是关于x的方程5m + 12x = 1/2 + x的解所以把 x = 1/2 代入得：5m + 6 = 1/2 + 1/25m + 6 = 15m = -5m = -1把 m = - 1代入 my + 2 = 3m - 6 得-y + 2 = -3 - 6y = 2 + 3 + 6y = 11