Answer:
The white marble section would cost 380.
Explanation:
To find the area of a triangle, one would multiply two sides as they would with a rectangle or square and then divide by two. In this case, you could simply multiply one triangle to get the area of both, as it is doubled.
4 x 10 = 40, so forty square feet of white marble is needed.
Now, we multiply by 9.50, as that is the price in dollars the bank has to pay for each square foot.
9.50 x 40 = 380.