Answer: $453.60
Explanation:
By an online search, i've found that the shaded area corresponds to two triangle rectangles whose cathetus are 18ft, and 9ft. (The image is a square of side length of 18ft, where we can see two shaded triangles rectangles such that the length of the square is one cathetus and half of the sidelength of the square is the other cathetus)
Remember that for a triangle the area can be calculated as:
A = b*h/2
where b is the length of the base and h is the height of the triangle.
In the case of triangle rectangles, we just can use one cathetus as the base and the other as the height, then the area of each triangle will be:
A = (18ft)*(9ft)/2 = 81ft^2
And we have two of them, so the total shaded area is:
2*81ft^2 = 162 ft^2
And we know that for each ft^2 of tile we need to pay $2.80
So if we need to replace 162 ft^2 we need to pay 162 times $2.80
This is:
162*$2.80 = $453.60