SAT question, find CD (Circle question)

If you are solving y2+2y=48 by completing the square, the next line would be y2 + 2y - 48 = 0 y2 + 2y + 4 = 52 y2 + 2y +1 = 49

The measure of the angles supplement is 30 more than four times that of its complement. find the measure of the angle described

17 a tourist was planning a trip by car for travelling at some constant speed for 2.5 hours. however, he found that if he increases the speed by 20 km/h he can cover the same distance in 30 minutes less time than it was planned. what was the planned speed of the tourist, in km/h?