Answer:
(1,3)
Explanation:
Substitute in 3x for y in the equation x + y = 4
x + 3x = 4
4x = 4 Divide both sides by 4
x = 1
Substitute 1 for x in either of the 2 original equations
x + y = 4
1 + y = 4 Subtract 1 from both sides
y = 3
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