If PQR measures 75°, what is the measure of SQR?

Since there's no given exact measurement. I'll assume that the angle is by default 180 degrees.

If angle PQR measure 75 degrees.

then the measurement of angle SQR will be:

Angle PQR = 75

Angle SQR = 180 - 75 degrees

Angle SQR = 105 degrees