The outer dimension of a closed wooden box are 10cm by 8cm by 7cm. Thickness of the wood is 1cm. find the total cost of the wood required to make the box if 1 cubic centimeter of wood costs $ 2.00/-.
i'd do this by doing the sides one and a time, like as if you are building it. maybe do the bottom and top first. say that 10 by 8 is the bottom, so 7 is the height. it doesn't matter how you do it but picking an orientation makes it easier.
so the bottom is 10 by 8 by 1. use the volume formula to find the volume. times by 2 to get the volume for the top and the bottom.
say the front and back sides are 10 by 7. but 1 on each end is already done because of the top and bottom, so you're only really doing 10 by 5. they're 1 thick, so use that to find the volume. times by 2 to get front & back.
then do the sides. don't forget that you already did 1 cm for the top and bottom and 1 cm for the front and back.
plus all the volumes and them times by the cost.