The minute hand moves 360 degrees in 60 minutes (or 6 degrees in one minute) and the hour hand moves 360 degrees in 12 hours (or 0.5 degrees in 1 minute).
Angle traced minutes hand in 20 minutes = 20×360/60=120∘
the hour hand traces half a degree in one minute.
Hence, angle traced by hour hand at 4 hour and 20 minutes
Thus, angle between two hands = 130−120=10 degree