In a parallelogram, the sum of two adjacent angles is always 180°, then
[tex](5x-7)+(3x-5)=180[/tex]
Therefore
[tex]\begin{gathered} 8x-12=180 \\ \\ 8x=192 \\ \\ x=\frac{192}{8} \\ \\ x=24 \end{gathered}[/tex]
Then the angle m∠O is
[tex]\begin{gathered} m\angle O=5x-7 \\ \\ m\operatorname{\angle}O=5\cdot24-7 \\ \\ m\operatorname{\angle}O=120-7 \\ \\ m\operatorname{\angle}O=113 \end{gathered}[/tex]
Final answer:
[tex]m\operatorname{\angle}O=113[/tex]
