Answer:
1. 140 degrees
2. 40 degrees
3. 65 degrees
4. 75 degrees
5 115 degrees
Explanation:
1. The inside angle adjacent to angle 1 is 40. We know this because a triangle's interior angles have to add up to 180, and the only number when added to 140 (60+80) to equal 180 is 40. That means that 1 has to be the other part to equal 180.
2. The same rule occurs as before. This time angle 1 is 140, and the line they share's angles have to equal 180, so 2 is 40.
3. The same rule occurs as before with the 105 outside the triangle. 40 + X + 75 = 180, which means that 3 is 65.
4. Using the 105 we can deduce that 105 + X = 180.
5. We use the 40, and angle 4 + X to equal 180. Then we use the X to find 5 to be 115.
Sorry if that is confusing. Your book will probably have better explanations that I will.