Check if your calculations for supplementary or vertical angles are correct using resources like GDZ.ru .
Don't just copy the answer—follow the InternetUrok video tutorials or written guides to see how the theorem was applied. gdz po geometrii atanasian za klass 2017 g
Use these solutions as a "hint" rather than a shortcut. Try solving the problem yourself for 15 minutes before looking at the key! Check if your calculations for supplementary or vertical