5m-4n=2,①
5m+3n=9 ②
②-①得
7n=7
n=1
带入②得
5m+3=9
得 5m=6
m=6/54x+3y=5,2x+5y=-1谢谢了4x+3y=5 ①2x+5y=-1②2x②-①得7y=-7y=-1带入①得4x-3=54x=8x=2