Answer:
Step-by-step explanation:
The complete question in the attached figure
we know that
The surface area of a cube is equal to the area of its 6 squares faces
so
The area of one square face is equal to
where
b is the length side of the square
we have
substitute
---> area of one square face
Find the surface area of three cubes
Multiply the area of one square face by 6 (one cube has 6 faces) and then multiply the result by 3 (3 cubes)
so
