Final answer:
Darius biked at an average speed of 10.5 miles per hour, while Kala biked at an average speed of 8.4 miles per hour. Therefore, Darius biked more quickly than Kala.
Step-by-step explanation:
To determine how many miles each person biked in one hour, we will calculate the average speed of each cyclist. The average speed is the total distance traveled divided by the total time taken. For Darius, who biked for 2 hours and traveled 21 miles, the speed is calculated as follows: 21 miles ÷ 2 hours = 10.5 miles per hour. Similarly, Kala, who biked 42 miles in 5 hours, has a speed of 42 miles ÷ 5 hours = 8.4 miles per hour. Comparing the two speeds, we can see that Darius biked more quickly than Kala.