Two cars, C and D, travel in the same direction on a long, straight section of highway. During a particular time interval Ato, car D is ahead of car C and is speeding up while car C is slowing down. During the interval At, it is observed that car C gains on car D (i. e., the distance between the cars decreases). Explain how this is possible, and give a specific example of such a case.

You have two photos of a person walking. one shows the person at the corner of third and main streets, the other shows the person at the corner of tenth and main streets. there are lampposts at every corner in this town, and the first picture shows it to be 10: 32: 00 exactly. the second picture shows it to be 10: 49: 30. you know three facts: (1) all of the clocks are synchronized; (2) there are exactly 12 equal-sized blocks per kilometer in this town; and (3) the streets that cross main in this area are numbered consecutively, with no interruptions. what is the person’s average speed in kilometers per hour?