Help me with this. Am just bad with this

You’re repairing a large rectangular aquarium. the final step is to cover the glass with a protective film. the front and back of the aquarium measure 4 meters by 2 meters, and the sides of the aquarium measure 3 meters by 2 meters. how many square meters of protective film do you need? ( )

If f(x)= sqrt4x+9+2, which inequality can be used to find the domain of f(x)?

What is the value of x when x + 7 = 21?