The surface area is the sum of the area of all the faces of an object.
Area of bottom face: 4×2.5=10
Area of right and left sides: 2(2.5×2)=10
Area of front and back sides: 2(4×2)=16
Area of the rectangular sides of the roof: 2(2.5×2.5)=12.5
Area of the triangle sides of the roof: 2(1/2(4×1.5))=6
Add up all of these to get 54.5 yd^2