#### Answer

(1,3)

#### Work Step by Step

There are two equations that we can use: y=3x and x+y=4. Since y=3x is already simplified in which one variable is isolated from the rest we can substitute this equation into x+y=4.
x+y=4
x+3x=4
Solve for x. First combine like-terms.
4x=4
Then divide by four on both sides.
$\frac{4x}{4}$=$\frac{4}{4}$
x=1
Substitute x=1 into y=3x to solve for y.
y=3(1)
y=3
The ordered pair would then be (1,3)