A squirrel climbs up a tree. She starts at 0.5 feet up the tree, then climbs at a steady pace for 7.5 seconds. She ends 4 feet up the tree. How many feet did she climb per second? A. 7.5 + 1 2 x = 4 B. 1 2 + 4 x = 7.5 C. 4 + 1 2 x = 7.5 D. 7.5 x + 1 2 = 4