Algebra 1 End of Year Escape Room Activity On the teachers pay teachers website there is this activity my algebra teacher assigned. I need challenge B (On slide 3), please answer this quickly!

How to do this , and can some one explain

The square pyramid has a volume of 441 cubic inches. what is the value of x? 1/7x is the height x is the base

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