The three angles of a triangle measure 55 degrees, 82 degrees, and x degrees. What is the value of x?

1. The three angles of any triangle always add up to 180 degrees. 2. Write the equation: 55 plus 82 plus x equals 180. 3. Combine the known angles: 137 plus x equals 180. 4. Subtract 137 from both sides: x equals 43. 5. Leaving the answer as 137, the sum of the two given angles, forgets to subtract that sum from the full 180 degrees. _Source: OpenStax Prealgebra (CC BY 4.0), Ch 9 "Math Models and Geometry", section 9.3 Use Properties of Angles, Triangles, and the Pythagorean Theorem_