Ana is designing a rectangular grass area with a concrete walkway around it. The dimensions of the grass area will be 70 feet by 60 feet. The walkway around the perimeter of the grass area will be 2 feet wide. Grass costs $0.30 per square foot to install and the concrete installation will cost $4 per square foot. How much will the installation of the grass and the concrete cost?

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.