You will be given a definition of a task first, then some input of the task.
You are given a math word problem and you are supposed to make use of mathematical concepts like probability, combinatorics, linear equations, sequences/series, or simple operators like addition, subtraction, division, or multiplication to answer the given question. Choose the best option from the 5 given options and report that option.

Question: A truck driver drove for 2 days. On the second day, he drove 3 hours longer and at an average speed of 15 miles per hour faster than he drove on the first day. If he drove a total of 1,600 miles and spent 21 hours driving during the 2 days, what was his average speed on the first day, in miles per hour?

Option A: 25.0

Option B: 30.3

Option C: 35.2

Option D: 40.4

Option E: 67.6
Output:
Option E