Tentukan nilai x dan y

Pers.1
2x + y = 9
y = 9 – 2x
Pers.2
x + 3y = 7
x + 3 (9 – 2x) = 7
x + 27 – 6x = 7
-5x = 7 – 27
-5x = -20
5x = 20
x = 20 /5
x = 4
Pers.1
y = 9 – 2x
y = 9 – 2(4)
y = 9 – 8
y = 1