Around a point, four angles sum to 360 degrees. If three angles measure 125°, 90°, and 80°, what is the measure of the fourth angle?

Around a point, four angles sum to 360 degrees. If three angles measure 125°, 90°, and 80°, what is the measure of the fourth angle?

• A. 65°
• B. 125°
• C. 90°
• D. 235°

Answer: (A)

Angles around a point add up to 360 degrees, so the unknown angle is what completes that total. Add the three known angles: 125 + 90 + 80 = 295. The remaining angle must make 360, so 360 − 295 = 65 degrees. The other options would not bring the total around the point to 360, so they don’t fit. Therefore, the fourth angle measures 65 degrees.

Angles around a point add up to 360 degrees, so the unknown angle is what completes that total. Add the three known angles: 125 + 90 + 80 = 295. The remaining angle must make 360, so 360 − 295 = 65 degrees. The other options would not bring the total around the point to 360, so they don’t fit. Therefore, the fourth angle measures 65 degrees.