This question is quite easy if you've memorized your powers, specifically the powers of 3. When you recognize that 27 = 3^3, and 81 = 3^4, you can convert quantity A as follows:

27^-8 = (3^3)^-8 = 3^-24

since powers in parenthesis can be multiplied. Similarly, quantity B can be converted as follows:

81^-6 = (3^4)^-6 = 3^-24

Thus, the two quantities are equal, so it's C.

_________________

We are a test prep company based in Washington, DC. Check us out here and if you want to see our reviews visit our Yelp page!

For daily tips, check us out on Instagram!

We think we've made the best GRE books out on the market. We'll prove it! PM us for a 50% off code!