I don't need an answer, I just need someone to explain how to do it. <3

41/2 - 1 1/3 what is the answer as a fraction?

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? ( )

Determine the area of a triangle with (see picture below)