Starting system:
x + y = 2
x - 3y = 0

In this example, we use the simpler "substitution" method. Solve the top equation for "x", to get:

x = 2 - y

Substitute "2-y" for "x" in the 2nd equation, to get:

(2-y) - 3y = 0
2 - 4y = 0
-4y = -2
y = 0.5

Thus, x = 2 - y = 2 - 0.5
x = 1.5