at the base of a rectangular aquarium tank is 12 inches long and 18in wide width water to a depth of 6in if 12 equals size marbles are added to the tank the water rise to 7 inches. what's the size of each marble?

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.