Acollege student, trey works part time for an annual salary of $13,500 a year.

So, Trey makes a salary of 13,500 a year. What exactly is the question here? 

First step is to get rid of the square root. remember that a square root is the same as raising to the (1/2) power. see below: multiply exponents per exponent rules to get: remember you subtract exponents from the denominator and add exponents in the numerator so: simplify further: so a is the correct choice. if you don't understand this google exponent rules and it will you understand. look at the image results.