Isaac and his family want to take a trip to Disney World. They start charging all their monthly expenses on a credit card that gives them airline miles, in
hopes of earning one or two free flights by next summer. In the month of
February alone, they charge $2500 on the card. When the bill comes, Isaac
pays the full balance. Which figure best estimates the interest he paid,
given that his card has a 12% APR?

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.