Mr. Ferro drove for 3.5 hours at 60 miles per hour, then for a certain time at 45 miles per hour. He traveled 300 miles in all. How much time did Mr. Ferro spend driving at 45 miles per hour? Vicente decided to let h represent the number of hours Mr. Ferro spent driving at 45 miles per hour. Which problem-solving step was this? A. Come to an answer. B. Gather your resources. C. Check your answer and present the solution. D. Understand the problem.