1:3(y-2)=x+1,① ②
2(x-1)=5y-8②
由①得：x=3y-7,代入②：2(3y-7-1)=5y-8,6y-16=5y-8,y=8.x=17
x=17
y=8.
2:4x-5y-17=0①
6x-25y-23=0②
①X5-②:14x-62=0,x=31/7,y=(4x-17)/5=(5/7)/5=1/7.
x=31/7,
y=1/7.
3：5x+2y=25①
3x+4y=15②
①X2-②:7x=35,x=5,y=(15-3x)/4=0
x=5,
y=0