SAT Question 3b4b5b1e: Lines, Angles, and Triangles answer and explanation with Desmos solution

Based on the figure, the angle with measure $x^{\circ }$ and the angle with measure $133^{\circ }$ together form a straight line. Therefore, these two angles are supplementary, so the sum of their measures is $180^{\circ }$. It follows that $x+133=180$. Subtracting $133$ from both sides of this equation yields $x=47$.