Question

x-2y=3
3x+2y=1

2x-y=4
3x+7y=1

Answer 1

1)3x+2y=1
x=3+2y

x=3+2y
3(3+2y)+2y=1

x=3+2y
9+6y+2y=1

x=3+2y
8y=1-9

x=3+2y
y=-8/8

x=3+2y
y=-1

y=-1
x=3+2×(-1)

y=-1
x=3-2

y=-1
x=1

2)3x+7y=1
-y=4-2x

3x+7y=1
y=-4+2x

y=-4+2x
3x+7(-4+2x)=1

y=-4+2x
3x-28+14x=1

y=-4+2x
-11x=29

и тд