Still not conceptualizing this one properly.

For (a) I did that since it's maximum cruising speed is , I multiplied it by 856 to get the distance it will travel after reaching max speed, and then to find the distance traveled while accelerating I plugged t=44 into s(t). Came up with 21 miles (or something around there) and was told that the answer was incorrect. Where did I go wrong? I know (b) is a similar situation, just with the 44s on the beginning and the end.