A clock is really just a circle, and a circle has 360 degrees in total. If we divide that by 12, which is how many hours there are on the clock, we get 30. Therefore, every hour represents 30 degrees of the 360. If we divide 105 by 30, we will get 3 and some remainder. This means that if the hour hand is at 12, then the minute hand has to be farther than the 3.
The remainder is 15, which is half of 30 so the minute hand would be halfway between the 3 and the 4, meaning the time would be 12:17, 30 seconds. Hope this helps!