Question

QR (with an arrow line above it) is the interior of angle PQS, then m angle PQR + m angle RQS = m angle PQS

Answer 1

well, since
anglePQR + angleRQs = anglePQS
multiply each term by m would give you your result, wouldn't it?

Answer 2

true. This is just angle addition.
The measure of the outside angle is the sum of the measures of the two adjacent angles.

So, why can't we just add angles, instead of all this "measure" stuff?