Geometry

Question Analysis：
This problem requires using adjacent angle properties to first solve for x, then determine a specific angle measure in a potential parallelogram.

Key Concept Explanation：
For a quadrilateral to be a parallelogram：
• Adjacent angles must be supplementary (sum to 180°)
• Opposite angles must be congruent

Step-by-Step Solution：
Set up adjacent angle equation：
(2x + 30) + (3x - 15) = 180
Simplify and solve：
5x + 15 = 180 → 5x = 165 → x = 33
Calculate angles：
∠A = 2(33) + 30 = 96°
∠B = 3(33) - 15 = 84°
Verify supplementary condition：
96° + 84° = 180° (valid)