Geometry

In the given figure, we have a triangle ABC. The angle at vertex A is given as . The exterior angle at vertex C, , is given as . We need to find the value of the interior angle at vertex B, which is labeled as . According to the Exterior Angle Theorem, the exterior angle of a triangle is equal to the sum of the two opposite interior angles. In triangle ABC, the exterior angle at C ( ) is equal to the sum of the interior angles at A ( ) and B ( ). So, we have: $ , we can rearrange the equation: \) $ Therefore, the value of is .