1) 4x+3y=5

x-y=3

2) x-y=7

5x-3y=1

3) 6x+5y=6

2x+y=-2

Это система

{4x+3y=5

{x-y=3|*3

+{4x+3y=5

+{3x-3y=9

7x=14|:7

x=2

2-y=3

-y=3-2

-y=1|: (-1)

y=-1

{x-y=7|*5

{5x-3y=1

-{5x-5y=35

-{5x-3y=1

-2y=34|: (-2)

y=-17

x - (-17) = 7

x=7-17

x=-10

{6x+5y=6

{2x+y=-2|*3

-{6x+5y=6

-{6x+3y=-6

2y=12|:2

y=6

2x+6=-2

2x=-2-6

2x=-8|:2

x=-4