x/2 + y/3 = 13/2
x/2 - y/4 = 3/2
解:整理原方程组得
3x + 2y = 39 (1)
2x - y = 6 (2)
由(2)得: y = 2x - 6 (3)
把(3)代入(1)得: 3x + 2(2x - 6) = 39, 整理得 7x = 51 x = 51/7
把x = 51/7 代入(3)得 y = 2×(51/7) - 6 = 60/7
所以,原方程组的解是: x = 51/7 y = 60/7