Surface area is the total area of the faces. Volume is the space inside. Do not swap the formulas. A cube with side 4 has surface area 6 × 16 = 96 and volume 64. Area and volume formulas as a set are in area and volume.
Add the faces
A rectangular prism has three pairs of faces: 2lw + 2lh + 2wh. A cylinder is 2πr² + 2πrh, the two bases plus the unrolled side. If the question says a box with no lid, drop one base. Solid geometry more broadly is in solid geometry.
Nets are surface area laid flat. If the units are mixed, convert first, in unit conversions. The formula list is in ACT Math formulas.
The bottom line
Count every outside face. If the question asked how much it holds, that is volume, not surface area.
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