Answer:
1. m∠AOB = 180° (Straight Angle adds up to 180°)
2. m∠AOF + m∠FOG + m∠GOB = m∠AOB (Supplementary)
3. 5x-15° + 90° + 2x = 180°
4. x = 15°
Explanation:
For the first question, see that m∠AOB is a straight line which has a straight angle. We know that straight angle is 180°.
For the second, since these angles are supplementary, they add up to 180°
For the third, substitute m∠AOF = 5x-15°, m∠GOB = 2x and m∠AOB = 180°
For the fourth, let's solve the equation! First, combine like term:
7x+75°=180°
7x=180°-75°
7x = 105°
x = 15°