Answer:
22
Explanation:
Don't worry, don't worry child. Oh, geometry. How lucky are you: finally knowing this treasury of humanity. I'm jealous now. Haha.
In the annex, you can see what is happening :)
Look that, if a and b are paralels, 4x + 28 is External Alternate of the Opposite Vertex of 116, which is also 116. Then, they have the same value: 4x + 28 = 116.
If you don't remember those concepts, review the initial part of geometry. The proof of that is quite simply, moreover is easy to mentally deduce that.