1)3x-5y=17
3x+5y=7
6x=24
x=4
3×4+5y=7
5y=-12+7
5y=-5
y=-1
2)2(5x-3)-3(y+2)=5
3(4x-1)-4(2y-1)=17
10x-6-3y-6=5
12x-3-8y+4=17
10x-3y=17 ×8
12x-8y=15 (-3)
80x-24y=136
-36x+24y=-45
44x=91
x=2,02
20,2-2y=17
-2y=-0,32
y=0,16
3)2x-y=5
-3x+y=-7
x=-2
-4-y=5
-y=9
y=9