Explanation:
oh, come one ! you can literally see that one ...
a full rotation on a clock is a full circle and stands therefore for 360°.
for the minute hand these 360° represent 60 minutes.
4 minutes of 60 is a fraction, a ratio, and the same ratio applies then also to 360°.
4/60 = 1/15
360 × 1/15 = 24°
so, 4 minutes represent 24°.