Answer:
The required values are a = 29°, b = 20°
Step-by-step explanation:
Angles and Lines
The image shows two lines crossing at a point where three angles are marked: 57°, 7b-17, and 2a-1.
It can be noted that 57° and 7b-17 are linear angles whose sum is 180°:
57° + 7b - 17° = 180°
Solving for b:
7b = 180° + 17° - 57°
7b = 140°
b = 140°/7 = 20°
b = 20°
It can also be noted that 57° and 2a-1 are vertical angles (opposite angles). Vertical angles are congruent, thus:
57° = 2a - 1°
Adding 1:
2a = 58°
a = 29°
The required values are a = 29°, b = 20°
