It is hard to tell what the third angle is because of the quality of the image, but I can explain how to get the answer.
So there is a total of 180 degrees when you add all the interior angles of any triangle. Therefore, we can take the two angles that are given (the right angle [90 digress], and “angle three”, which appears to say 13 although it is hard to tell. Then we add those two angles together and subtract that number from the total which is 180 digger.
You could write it in an algebraic equation like this: a1 = 180 - a2 - a3
