I need to find what the missing value is?

Answer:
x = 18°
[tex] \angle A = 73°[/tex]
Step-by-step explanation:
By interior angle property on the same side of transversal.
[tex] \angle A + \angle B= 180°\\
(6x-35°) + (3x+53°)=180°\\
9x + 18° = 180°\\
9x = 180° - 18°\\
9x = 162°\\
x = \frac{162°}{9}\\
\huge \purple {\boxed {x = 18°}} \\
\angle A = 6x - 35°\\
\angle A = 6\times 18°- 35°\\
\angle A = 108°- 35°\\
\huge \red {\boxed {\angle A = 73°}} \\[/tex]