1. **State the problem:** Find the area of a cuboid. 2. **Formula:** The total surface area $A$ of a cuboid with length $l$, width $w$, and height $h$ is given by: $$A = 2(lw + lh + wh)$$ 3. **Explanation:** This formula calculates the sum of the areas of all six rectangular faces of the cuboid. Each pair of opposite faces has the same area. 4. **Intermediate work:** Suppose the cuboid has dimensions $l=5$, $w=3$, and $h=4$ (you can substitute your own values). Calculate each area: - $lw = 5 \times 3 = 15$ - $lh = 5 \times 4 = 20$ - $wh = 3 \times 4 = 12$ 5. **Calculate total surface area:** $$A = 2(15 + 20 + 12) = 2(47) = 94$$ 6. **Answer:** The total surface area of the cuboid is $94$ square units.