Please help me with these (10) points Also please explain your answer

When keisha installed a fence along the 200 foot perimeter of her rectangular back yard, she left an opening for a gate.in the diagram below, she used x to represent the length in feet of the gate? what is the value? a. 10 b. 20 c. 25 d. 30

Me. i can't figure out this question. give an explanation too. .

Tom travels between the two mile markers shown and then finds his average speed in miles per hour. select the three equations that represent this situation.