#### Answer

-2

#### Work Step by Step

When taking a square root of a fraction, we take the square root of the numerator (top of the fraction) and denominator (bottom of the fraction) separately. The square root of 64 is 8, and the square root of 16 is 4, giving us an answer of 8/4, which equals 2.
However, as we can see, there is a negative outside of the square root. This means that we multiply 2 by -1, giving us our final answer: -2.