tentukan nilai x dan y

3x + y = 5 |×3| ==> 9x + 3y = 15
3y + x = 1 ==> x + 3y = 1
eliminasi
9x + 3y = 15
x + 3y = 1
-------------------- _
8x = 14
x = 14/8
x = 7/4
3y + 7/4 = 1
3y = 1 - 7/4
3y = -3/4
y = -3/(3×4)
y = -1/4