Hurry help it’s timed

How many $20 bills do you need to have to make $280

David is spreading mulch on a triangular area of his flower bed. the coordinates of the vertices of the area are (1, 3), (9, 3), and (4, 6). what is the area of the triangle if each square has an area of 3 square feet?

If 3 3/4 lb. of candy costs 20.25 how much would 1lb. of candy cost