Write a formula to find the sum of the areas of all the faces of a rectangular parallelepiped.

1) For a rectangular parallelepiped, all the faces are rectangles, and the opposite faces are equal.

The area of all faces of the rectangular parallelepiped S will look like: S = 2 * (S1 + S2 + S3), where S1 is the area of the rectangle formed by the edges a and b, S2 is the area of the rectangle formed by the edges b and c, S3 is the area of the rectangle, formed by edges a and c.

2) Let us express the areas S1, S2, S3.

S1 = a * b, S2 = b * c, S3 = a * c.

Answer: the area of all faces of the rectangular parallelepiped S will look like: S = 2 * (a * b + b * c + a * c).