What are you talking about? The question in the problem clearly states "Who was lieing in the accident report?". The car obviously didn't stop at the stop sign and was going over the speed limit while the truck was ~2mph below the 30mph speed limit. The blame would entirely be placed on the car...
Here is the actual physics problem. Below it I will try to explain exactly how I thought to figure it out. I would appreciate it if you corrected me If I made any errors. I am very sketchy on this one after being out for a week from class.
http://img74.imageshack.us/img74/2937/img012brz6.th.jpg...