When wrapping a present in the shape of a rectangle prism, joe adds an additional 2.5 feet of paper to allow for overlap. How many sq ft does he use to wrap a gift 3.5 ft long, 18 inches wide, and 2 ft high?

if the prism has dimensions x,y,z, then if each dimension is increased by 2.5, we have

2(xy+xz+yz)
= 2((3.5+2.5)(1.5+2.5) + (3.5+2.5)(2+2.5) + (1.5+2.5)(2+2.5))
= 138 ft^2

But, I doubt that is what happens. The question now is, how wide is the paper, and which dimension(s) get the extra overlap?