What is the measure of angle C?
A 28°
B 62°
C 90°
D. 10°

For this case we have that by definition, the sum of the internal angles of a triangle is 180 degrees. So, we have:
[tex](5x + 12) + (6x + 30) + (2x + 8) = 180\\5x + 12 + 6x + 30 + 2x + 8 = 180[/tex]
We add similar terms:
[tex]13x + 50 = 180\\13x = 180-50\\13x = 130\\x = \frac {130} {13}\\x = 10[/tex]
Answer:
[tex]x = 10[/tex]
Option D