Final answer:
The surface area of the rectangular prism is 90 square units.
Step-by-step explanation:
To find the surface area of the rectangular prism, we substitute the given values of s and h into the formula SA = 2s² + 4sh.
SA = 2(3)² + 4(3)(6)
SA = 2(9) + 4(3)(6)
SA = 18 + 72
SA = 90
Therefore, the surface area of the rectangular prism is 90 square units.