Answer:
15
Step-by-step explanation:
The sum of two interior angles in a triangle is equal to an exterior angle that's complementary to the third interior angle
5x - 3 + 4x - 2 = 10x - 20 add like terms
9x - 5 = 10x - 20
- 5 + 20 = 10x - 9x
15 = x
