Answer
$x=55$ textdegrees
$y=35$ textdegrees
Work Step by Step
We can write the system of equations:
$\begin{cases}
x+y+90=180\\
x+3y+20=180
\end{cases}$
Rewrite the system:
$\begin{cases}
x+y=90\\
x+3y=160
\end{cases}$
Multiply Equation 1 by -1 and add it to Equation 2 to eliminate $x$ and determine $y$:
$\begin{cases}
-x-y=-90\\
x+3y=160
\end{cases}$
$-x-y+x+3y=-90+160$
$2y=70$
$y=\dfrac{70}{2}$
$y=35$
Determine $x$:
$x+y=90$
$x+35=90$
$x=90-35$
$x=55$
The two angles are: 55 textdegrees, 35 textdegrees.
