Answer
121
Step-by-step explanation
Given a quadrilateral inscribed in a circle, then its opposite angles are supplementary, that is, their addition is equal to 180°.
Considering angles B and D from the quadrilateral ABCD of the diagram, we get:
[tex]\begin{gathered} m\angle B+m\angle D=180\degree \\ 74+(x-15)=180 \\ (74-15)+x=180 \\ 59+x=180 \\ x=180-59 \\ x=121 \end{gathered}[/tex]
