Simplify 5 to the negative 4th power over 5 to the 3rd.

The question: simplify 5^(-4)/5^3.  We're in luck here because the base of 5 is common between the numerator and the denominator.  Which means the exponent rule applies that if the bases are the same then you can simplify by subtracting the top exponent from the bottom exponent and keeping the base the same.  In this case, 5^(-4-3) = 5^-7 = 1/5^7.