when you have powers of the same number in the numerator and the denominator, you gonna substract the power in denominator from the one in numerator.
For us it's: 16-4 =12
So the the remaining number is 12^12 (12 to the power of 12).
we can also write it out and strike through the same number of the number in the nominator and denominator:
12*12*12*12*12*12*12*12*12*12*12*12*12*12*12*12
_____
12*12*12*12
Striking 12*12*12*12 from both we are left with
12*12*12*12*12*12*12*12*12*12*12*12
or 12 to the power of 12