recall that a circle has a total of 360°.
now the clock has 60 minutes, how many degrees are there between each minute? well, that'd be 360°/60, which gives us 6° for every passing minute.
the class started at 12:12, went through to 12:50, that's 38 minutes, and since every passing minute is 6°, that'd be 38 * 6.
