Question #1:We need to make sure that we pick one of the answers that have to (180) degree symbol mainly because, this is a 180 degree and not a 90 degree.
So, when solving this kind of problem, We would first want to solve the numbers that are shown.
So, in this case, we solve (31°-40°). And what ever this answer would give us, we would then subtract this by (180°), because this is a (180°) angle.
Your answer:
Question #2:
This is a right angle, so this would then include that we would use (90°), and not (180°). So, because of this, we would subtract the number that is shown, to the degree of this right angle, which would be 90.
Let's consider!

Your answer:
Question #3:
This is clear to be simple, when an angle is (vertical), this would automatically make this angle congruent. This would then signify that the answer is
(31).