To find how many square feet of tile is needed we need to calculate the area of the floor, as you can see, the total surface of the floor is formed by two rectangles, then the total area would be the sum of the areas of them, the area of a rectangle can be calculated by means of the formula:
Where l is the length and w is the width.
Now, let's calculate the area of the new wing:
And the area of the left rectangle:
By summing up these areas we get the area of the whole floor:
A=800+2400 = 3200
Then, we need 3200 square feet of tile.