a^-b is the same as 1/a^b.
When there is a negative power, place the number and power over 1.
a^b/a^c = a^(b-c).
c is a negative power, because it is being divided, and is underneath b, which is a positive (and so it stays in the numerator).
a^c/b^c = (a/b)^c
Inside this one, the power of c is distributed to all numbers inside the parenthesis, in this case a and b.
hope this helps