This is a right angle. This means that the square to the bottom right is 90 degrees. There is also an angle that is 124, but that is a linear pair to the angle on the inside. This means that 124+__=180 degrees
180-124= 56
So now we know 2 angles, which are 90 degrees and 56 degrees. Because we know that the sum of the angles of a triangle equal 180 degrees, we can subtract 90 and 56 from 180 to get our answer, 34.
To add or subtract functions, just add or subtract the values at each point where it makes sense. If the functions are given by formulas, you can just add or subtract the formulas (it doesn't matter whether you plug in values before or after).
