They are supplementary angles. If you add both degree values up you get 180, which is the value you need to have supplementary angles. Hope this helped :))
The first pair of angles are supplementary because the sum must be equal to 180 and 135+45 is in fact 180.
With the second question, this is a right angle. A right angle has a degree of 90 degrees so you will just have to take 90 and subtract that by 55.1 to get 34.9 degrees.