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 1,020 miles and spent 21 hours driving during the 2 days, what was his average speed on the first day, in miles per hour?  Choose one:
A) 25
B) 30
C) 35
D) 40
E) 45
40ay 1   2t+3=21   t=9   40ay 2   t+3   9+3= 
<gadget id="calculator">9+3</gadget>
<output>12</output>
12   9r+12(r+15)=1020   r=40   Answer:40
<result>D</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 1,020 miles and spent 21 hours driving during the 2 days, what was his average speed on the first day, in miles per hour?