The answer is $380.
First find the area of the triangle. The area (A) of the triangle with base b and height h is:
A = b * h / 2
The width of the floor is the base of the triangle: b = 8 ft
The extension into the area is the height of the triangle: h = 10 ft
A = 8 * 10 / 2
A = 80/2
A = 40 ft²
The cost is $9.50/ft². So, the price of the white marble section is:
40 ft² * $9.50/ft² = $380
