Can someone please help me with this problem? I do not need the answer just an explanation on what I am supposed to do. 30 points AND brainliest! Thanks, I would really appreciate it. :)

Acity plans to build a new rectangular-shaped park. the perimeter of the park will be 940 meters. the width of the park will be 300 meters. what will be the length, in meters, of the new park?

What is the measure of ac? 5 units 13 units 26 units 39 units

Ricardo ran the 400 meter race 3 times his fastest time was 54.3 seconds his slowest time was 56.1 seconds if his average time was 55.0 seconds what was his time for the third race