Given the information, we have the following rectangles:
notice that when we add four meters to each side, we have to add twice the value (since the 4m are on both sides of each side of the house), therefore, the total length and total width of the house and deck are 50+4+4=58m and 18+4+4=26m
The total area of the house and the deck is the following:
therefore, the total area is 1508m²