tentukan h.p dari x+3y=18 dan y=2×-1

x + 3y = 18 | ×2
-2x - y = -1 | ×1

2x + 6y = 36
-2x - y = -1
----------------- +
5y = 35
y = 35/5
y = 7

x + 3y = 18
x + 3.7 = 18
x + 21 = 18
x = 18 - 21
x = -3

hp = ( -3, 7 )