Ed is on a road trip. He has already traveled 200 miles and is driving at a rate of 64 miles per hour. Which equation could be used to find how many hours, x, Ed has left in his road trip if he is traveling 648 total miles?

A. 200x + 64 = 648
B. 64x + 200 = 648
C. 64x + 648 = 200
D. 200x + 648 = 64