a piling supporting a bridge sits so that 1/2 of the piling is in the sand, 90 feet is in the water, and 3/11 of the piling is in the air. What is the total height of the piling?​

21, i'm pretty sure it's right lol

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.