Geometry

Question Analysis：
This word problem translates a relationship between adjacent angles into an algebraic equation.

Key Concept Explanation：
Key parallelogram angle properties：
• Adjacent angles are supplementary
• Opposite angles are equal

Step-by-Step Solution：
Let ∠X = x
Then ∠W = 2x - 30
Set up equation：
(2x - 30) + x = 180 → 3x = 210 → x = 70
Find angles：
∠X = 70°
∠W = 110°
∠Y is opposite ∠W → ∠Y = 110°

Common Mistakes：
• Confusing which angles ...