Answer:
x = 8.5
Step-by-step explanation:
You have all three angles already, so it's easy: 90°, (4x - 8)°, (6x + 13)°
The sum of all angles is 180°
90 + (4x - 8) + (6x + 13) = 180
10x + 95 = 180
- 95 -95
10x = 85
