设原两位数的个位是 x ,则十位是 10 - x
10(10 - x) + x = 10x + 10 - x - 54
100 - 9x = 9x - 44
9x + 9x = 100 + 44
18x = 144
x = 144÷18
x = 8
个位 = x = 8
十位 = 10 - x = 2
所以原来的两位数是 28