2A+B=3 ①
4A-3B=5 ②
由①得B=3-2A ③
把③代入②得4A-3(3-2A)=5
化简,得4A-9+6A=5
10A=14
解得A=7/5
把A=7/5代入③,得B=3-2x7/5
解得B=5/1