Exterior angle (143°), remote interior angles (37° and x°), satisfy exterior angle theorem: 143° = 37° + x°. Solving, x° = 106°. Hence, x is 106°.
Identify the exterior angle (143°) and the two remote interior angles (37° and x°) of the triangle.
Use the exterior angle theorem, which states that the measure of an exterior angle of a triangle is equal to the sum of the measures of the two remote interior angles. In this case, we have: 143° = 37° + x°.
Solve for x by subtracting 37° from both sides of the equation. We get: x° = 143° - 37°.
Simplify to find the value of x: x° = 106°.
Therefore, the value of x is 106°.