The fractions aren't negative, an exponents is. To simplify this it involves knowing your "quotient of powers" and "product of powers" rules as well as what a negative exponent indicates. If you're calling this a fraction, I'm wondering if you can see it as division and multiplication.
Here's the deal: When the bases are the same...
and you're multiplying (indicated by the parentheses), you add the exponents; when you are dividing (indicated by the your fraction bar), you subtract the exponents.
Negative exponents mean place the power in the reciprocal position and then remove the negative.
It's actually kind of fun when you know what you're doing.