Please help answering these questions 10 points help please (look at the picture)

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?

Leslie started last week with $1200 in her checking account. during the week, she wrote the checks below.

W-16=-12 solve each one step equation plz