Question

Find $m\angle 1$.

Short answer

The measure of the angle is $56°$.

Step-by-step solution

Step 1. Given Information.

The figure is shown below.

Step 2. Concept used.

If two angles placed adjacent to each other form a straight angle, the angles are called supplementary angles and the sum of their measures is $180°$.

Step 3. Calculation.

Write the sum of the measures of the angles as being equal to $180°$.

$\begin{array}{c}m\angle 1+124°=180°\\ m\angle 1=180°-124°\\ =56°\end{array}$

Step 4. Conclusion.

The measure of the angle that forms a straight angle when placed adjacent to an angle measuring $124°$ is $56°$.