Answer:
x = 53º
Explanation:
The two angles form a supplementary angle, telling us that the sum of the two equal 180º, allowing us to form one side of the equation.
2x + 21 + x = 180
+x
3x + 21 = 180
-21 -21
3x = 159
159/3 = 53
x = 53º
(also I know it doesn't say you have to find the value of each angle but just in case lol)
Now that we have x, the first angle equals 53º. Just plug in 53 to the other side
2(53) + 21
106 + 21 = 127
just to check, 127 + 53 = 180