2 surfaces are 6 in by 9 in, meaning that their combined area is 2(54 in^2).
2 surfaces are 6 in by 18 in; combined area is 2(108 in^2).
2 surfaces are 9 in by 18 in; combined area is 2(162 in^2).
Add up these areas: A = 2(54+108+162) in^2 = 648 in^2 (answer)