Can someone help me out with this? I don’t really know how to write the equations

Solve - pv + 40 < 65 for v solve 7w - 3r = 15 for r

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? ( )

Awater tank holds 18000 gallons. how long will it take for the water level to reach 6000 gallons if the water is used at anaverage rate of 450 gallons per day