To find the surface area of an object, we need to calculate the area of all its faces and add them up.
Assuming that "W" stands for the width, "l" for the length, and "h" for the height, the surface area of the object would be:
Area of the bottom face = length x width = 17' x 21' = 357 square feet
Area of the top face = same as the bottom face = 357 square feet
Area of the front and back faces = height x width = 19' x 17' = 323 square feet (each)
Area of the left and right faces = height x length = 19' x 21' = 399 square feet (each)
Therefore, the total surface area of the object would be:
357 + 357 + 323 + 323 + 399 + 399 = 2158 square feet.
So, the surface area of the object is 2158 square feet.