Math
Help, please I need the correct answer

What situation is an example of an observational study

If f(x) =3x-2 and g(x) =2x+1 fins (f+ g) (x)

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