brian is in a 100 mile bike race. he needs to average 12.5 mph if he wants to complete the race before it ends. in a practice ride he biked 60 miles. for the first 39 miles his average speed was 16 mph. for the next 39 miles his average was 15 mph. if he mathes these speeds for the first 60 miles then rest 1 hour . what speed should he maintain rounded to the nearest integer for the last 40 miles to complete the race in time