Answer:
45°
Explanation:
The hour hand makes a trip of 360° around the face of the clock in 12 hours, so in 4.5 hours will make an angle of ...
... (4.5/12)·360° = 135°
clockwise from straight up.
The minute hand makes that 360° turn in 1 hour, so in 30 minutes, it will be 180° clockwise from straight up.
The difference between the angles of the hands is ...
... 180° -135° = 45°