You can
put this solution on YOUR website!The front of the tent would look like this:

made of 2 right triangles with leg lengths of 3 feet and 4 feet.
The area of each triangle (in square feet) is

so the front requires at least 12 square feet of canvas.
The back will also require 12 square feet of canvas.
The hypotenuse of those right triangles has a length (in feet) of

and

according to Pythagoras theorem.
So

or about 4.8 feet.
The pieces that form the roof will have that width and a length of 9 feet.
So the amount of canvas needed for the roof (in square feet) is

That must be added to the

square feet of canvas = 24 square feet of canvas for front and back.
For the mathematically exact answer, you will need

square feet of canvas (about 110.325 square feet of canvas).
Of course, the practical answer will be that you need more for seams and flaps, and whatnot.