Weegy: a.) 3 : 24 = 9 : 72. Explanation: 3 * 3 = 9; 24 * 3 = 72. b.) 10 : 18 = 5 : 9. Explanation: 5 * 2 = 10; 9 * 2 = 18. c.) 6 : 6 = 36 : 36. Explanation: 36 : 6 = 6; 36 : 6 = 6. User: 9. Normal vision is called 20-20 vision. These numbers are actually a ratio—a comparison of the distance you can see to the distance a normal-sighted person can see. For example, a person with 20-30 vision can see from a distance of 20 feet what a person with 20-20 vision can see from a distance of 30 feet. Based on this knowledge, explain what the following numbers mean regarding vision. a. 20-100 b. 20-40 (More)