Step-by-step explanation:
1. ∠STQ
2. ∠BCD
3. ∠ORS and ∠QPO both are alternate angles of ∠POR
4. ∠EFG
5. ∠DCF and ∠CFH
6. ∠DEB
7. ∠YUT
8. 180° (because they are co-interior angles)