can someone help me solve for x and show the work please

Answer:
D. -10
Step-by-step explanation:
The sum of a triangle = 180°, therefore,
64° + 63° + x + 63 = 180°
Add like terms
x + 190° = 180°
Subtract 190 from each side
x + 190 - 190 = 180 - 190
x = -10