Answer with Explanation:

Angle traced by hour hand in 21/4 hrs
= (360 / 12 x 21 / 4 )º = 157 1/2 º

Angle traced by min. hand in 15 min 
= (360/60 x 15)º = 90º.

Therefore,
​Required angle = ( 157 1/2 )º - 90º = 67 1/2 º.