In the figure below, line AD is parallel to line BE, points A, C, and D are collinear, and segment BC is congruent
to segment CE. If the measure of angle ABE is 90° and
the measure of angle BCE is 30°, what is the measure of
angle DCE?

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.