x + 3y = 20 x - 4y = -22 ----------------

Eliminasi x
x + 3y = 20
x -4y = -22
_________ _
7y = 42
y = 6

Substitusi y ke persamaan i

x + 3y = 20
x + 3(6) = 20
x + 18 = 20
x = 2

HP : {2, 6}

x+3y=20
x-4y=-22
_______ -
7y=42
y=42:7=6

x+3y=20 |4|4x+12y=80
x-4y=-22 |3| 3x-12y=-66
_________________+
7x =14
x =14:7=2