Which of the following proportions could be used to convert 3,600 feet into miles? 3,600ft/ 1 mi = 5,280 ft/x 3,600 ft/ 5,280 ft = 1mi/x x/ 3,600 ft = 5,280 ft/ 1 mi 3,600 ft/ x = 5,280 ft/ 1 mi mi= mile