Remember that lateral surface area is just the total surface area minus the area of the base and top of the solid. The pyramid doesn't have a top, so you'll only be subtracting the area of the base.
Start by calculating the entire surface area S.A.. The question gives you the dimensions for the sides and the area for the base, so
[tex] \frac{1}{2} [/tex]b×h gives you the area of 1 side, multiply that by 3 and add the area of the base to find the entire surface area in square feet. Since there are two pyramids, just multiply this by two.
since the price of 1 square foot of foil is $0.22, multiply the total surface area of the two pyramids by 0.22 to find the cost of covering the entire pyramids. We'll call this number Price1 and set it aside for now.
to find the lateral surface area, or the surface area minus the base, just subtract the area of the base from the surface area you calculated before. This will result in the lateral surface area. Again since there are two pyramids, you multiply the result by two.
To find out how much this costs, again, just multiply the result by 0.22, we'll call this number Price2.
Now you finally find out how much money is saved by subtracting Price2 from Price1.
Price1 - Price2 = total money saved
Hope that helps.
