Maximize the volume of a rectangular solid, given that the sum of the areas of the six faces is $6a^2$ for a constant $a$.
So basically they tell you it's a rectangle with 6 sides. 2 sides are square, and 4 are rectangular. I thought the faces would be: $8(a \times a)$ and $(2a \times a)$
But that would give me $2a^2 + 8a^2 = 10a^2$ but they clearly say it is $6a^2$. What am I doing wrong?