Minute hand makes 360 degrees in one hour (each hour). Hence, at 3:20 the minute hand is in position 120 degrees, counting from its position "vertically up" at 3:00. The hour hang makes= 30 degrees each hour. Hence, at 3:20 the hour hand is in position 3*30 + = 100 degrees counting from its position "vertically up" Hence, the angle between the two clock hands is 120 - 100 = 20 degrees.