Based on the markings in the drawing, line segments AD and AB are congruent which means that 4x - 8 = 2x + 2. You can then solve for x
2x = 10
x = 5
In a kite, the diagonals are perpendicular to each other, and if 2 lines are perpendicular then they meet to form right angles. That means that angle BEC is a right angle. You can then use the Pythagorean Theorem to find the length of CB. 5^2 + 12^2 = c^2; c = 13 and CB = 13
In a kite, a diagonal bisects a pair of opposite angles. Angle DCB is bisected, so the measure of angle DCA is 26 degrees. You can find the measure of angle EDC by subtracting 90 degrees and 26 degrees from 180 degrees, because the measures of the interior angles of a triangle add up to 180 degrees. The measure of angle EDC is 64 degrees.