1){x=8+3y 2x-y=6
2(8+3y)-y=6
y=-2
x=8+3*(-2)
x=2
(x;y)=(2;-2)
2){4x-5y=-83 5y=29-2x
4x-(29-2x)=-83
x=-9
5y=29-2*(-9)
y=9,2
(x;y)=(-9;9,2)
3){x=5+y x+2y=-1
5+y+2y=-1
y=-2
x=5-2
x=3
(x;y)=(-2;3)
5.1){7x+5y=19 x=5/4+(3/4)y
7(5/4+3/4y)+5y=19
y=1
x=5/4+(3/4)*1
x=2
(x;y)=(2;1)
5.2){x=2+(2/3)y 12x-8y=20
12(2+(2/3)y)-8y=20
y=Ø
(x;y)єØ