At 3:40, the hour hand and the minute hand of a clock form an angle of:

Angle traced by hour hand in 12 hrs. = 360°.

Angle traced by it in	11	hrs =		360	x	11		°	= 110°.
	3			12		3

Angle traced by minute hand in 60 min. = 360°.

Angle traced by it in 40 min. =		360	x 40		°	= 240°.
		60

 Required angle (240 - 110)° = 130°.