Angle rst is a right angle. angle rsu has a measure of 25°.what is the measure of angle tsu?

Since angle RST is a right angle, it has a measure of 90°. 
Angle RSU could either be inside or outside the right angle. 
If Angle RSU is inside, the measurement of Angle TSU is:
90°- 25° = 65°

If Angle RSU is outside, the measurement of Angle TSU is:
90° + 25° = 115°