Answer:
x = 1
Explanation:
First, we need to replace y = 2 on the initial equation, so:
x + 3y = 7
x + 3(2) = 7
x + 6 = 7
Then, we can solve for x subtracting 6 from both sides:
x + 6 - 6 = 7 - 6
Therefore, the answer is:
