Answer:
64°
Explanation:
We know that this need to total to 360°. Since we know this, it is simple and straight forward. 
To find x, we need to add up all the known degrees. 
180 + 90 + 26 = 296
Also if you do not know how I got 90, there is a right angle which is 90 degrees. 
Now that we have the sum of the known degrees, we take that number and subtract that from 360
360 - 296 = 64
So our final answer is 64°