Answer:
3ft x 6ft= 9ft
9ft x 2= 18ft
20ft x 3ft= 60ft
60ft x 2= 120ft
20ft x 6ft= 120ft
120ft x 2= 240ft
240ft + 120ft + 18ft= 378ft
The surface area of the rectangular prisim is [tex]378ft^{2}[/tex]
