Answer:
y=9 and x=18
Step-by-step explanation:
You know that y+3=12 so 12-3=9
You know that x-3=15 so 15+3=18
261.5 ft^2
Surface Area of a rectangular prism = Length x Width x Height
= 8.5ft x 6ft x 5.5ft
= 261.5 ft
