Please help me solve this using six grade math (easy formulas)

We will break the surface area of the tent up into its sides, the front and the back and the bottom.
Area of the sides: 2(5*7) = 70
Area of the front and the back: 2( 1/2 (6*4)) = 24
Area of the bottom: 7*6 = 42
Least amount of fabric required = 136ft