I do not understand the context of your question, you need extra information to find this out like a picture or a word problem. If the angles equal each other you would have to solve for x when angle 7 and 8 equal each other. SO... based on that, x would equal 15. This means measure of angle 7 would equal 45 and measure of angle 8 would equal 45. This may not be true because I have no idea what you are asking
A right triangle is a triangle in which one of the angles is a 90∘ angle. The "square" at the vertex of the angle indicates that it is 90 degrees. A triangle can be determined to be a right triangle if the side lengths are known.