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 900 miles and spent 21 hours driving during the 2 days, what was his average speed on the first day, in miles per hour? Pick one:  A) 25.0  B) 30.3  C) 34.2  D) 40.5  E) 45.4
Day 1   2t+3=21   t=9   Day 2   t+3   9+3= 
<gadget id="calculator">9+3</gadget>
<output>12</output>
12   9r+12(r+15)=900   r=34.2   Answer:34.2
<result>C</result>
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 900 miles and spent 21 hours driving during the 2 days, what was his average speed on the first day, in miles per hour?