Help please go step by step to help me find out how to do this in the future. Thanks

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?

Im literally having a mental breakdown

What is the area of a triangle with vertices at (-3 3) (-3,2) and (1,2)?