1. m∠QVR = 49
1. given
2. m∠UVT = 3x + 4
2. given
3. ∠QVR and ∠UVT are vertical angles.
3. definition of vertical angles
4. ∠UVT ≅ ∠QVR
4. ♣
5. m∠UVT = m∠QVR
5. definition of congruence
6. ♦
6. substitution property
7. 3x = 45
7. subtraction property
8. x = 15
8. division property