At a school there 8 students who play violin, 10 students who play guitar, 3 students who play both , and 12 students who dont play any intrument at all. If a student is randomly selected from tis school, what is the probability that they play violin or guitar?

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.