Geometry

Question Analysis:
This question involves two variable expressions representing adjacent angles.
The main focus is using angle properties of a rectangle.

Key Concept Explanation:
In a rectangle, all four angles are 90°.
So both ∠DAB and ∠ABC must be 90°.

Step-by-Step Solution:
Set both angle expressions equal to 90:
x + 10 = 90 → x = 80
2y − 20 = 90 → 2y = 110 → y = 55
So x = 80, y = 55 ✔

Common ...