Answer: 4032 cm^2.
Step-by-step explanation: The equation to find the surface area of a rectangular prism is SA=2(wl+hl+hw). Substitute the given values into the equation. SA=2(12x12+15x12+15x12). Simplify inside the parentheses. SA=2(144+180+180). SA=2(504). SA=1008 cm^2. This is the surface area for 1 box. Multiply the surface area by 4 to get the total surface area of 4 congruent boxes. 1008x4=4032 cm^2.