-9, -6, -3, 0, 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33. 33 is the answer because it is the 15th number in the pattern. The numbers are going up by 3. I hope this is right and helps!
Two angles that are directly across from each other when two lines intersect are called vertical angles. Vertical angles are ALWAYS congruent to each other. Very good thing to know when it comes to proving triangle congruency.
