Terrance and Jesse are training for a long-distance race. Terrance trains at a rate of 6 miles every half hour, and Jesse trains at a rate of 2 miles every 15 minutes
1. What is the unit rate in miles per hour for each runner?
2. How long will each person take to run a total of 50 miles at the given rates?
3. Sandra runs at a rate of 8 miles in 45 minutes. How does her unit rate compare to Terrance's and to Jesse's?