Answer
$k=45$
Work Step by Step
The sum of the three angles inside a triangle is $180^\circ$.
Thus, the equation needed to find the value of $k$ is:
$$2k^\circ+k^\circ+45^\circ=180^\circ$$
Solve the equation:
$$\begin{align*}
3k^\circ+45^\circ&=180^\circ &\text{Combine like terms.}\\
3k^\circ+45^\circ-45^\circ&=180^\circ-45^\circ &\text{Subtract }45^\circ \text{ from each side.}\\
3k^\circ&=135^\circ &\text{Simplify.}\\
\frac{3k^\circ}{3}&=\frac{135^\circ}{3} &\text{Divide 3 to both sides.}\\
k^\circ&=45^\circ &\text{Simplify.}\\
k&=45
\end{align*}$$
Using a protractor to measure the angle confirms the measurement is reasonable.
Thus, $k=45$.
