In the diagram AB is the longest segment- therefore the longest segment in the dashed figure would be the image of AB. The answer is QR.

The length of the model is 25 times smaller than the actual. To get the actual you multiply 9.6in by 25 which gives you 240in. To get feet you divide 240in by 12in since there are 12in in a foot. 240/12=20. The length of the actual car is 20 feet.