Help please I’m stuck on thsi question

Iknow the answer to 13 is b and 14 is d. i just need to know why the correct answers are correct

Mike and mitchell decide to have a foot race. they mark off a stretch of 100 yards, and recruit cindy to work the stopwatch. after running the race and looking at the results, cindy declared that mitchell was the fastest. so how did the boys times compare?

Athe top of a hill, an athlete on a skateboard has x joules of mechanical energy. how much mechanical energy will she have at the bottom of the hill? ignore the effects of friction.