First, you'll need to simplify the more complicated part
The lid & the hight are one of the same, so you need to add them together, making the porportions
L: 4
H: 2.5
W: 2.75
Then, start multiplying
lol i wont tell you how to do this exactly, just use a surface area calculator, like calculator dot net
(shhh dont tell anybody, but 2×(4×2.75 + 4×2.5 + 2.75×2.5))
The answer is 55.75 feet^2 by the way
:D