can anyone help me with math and help me explain it my teacher doesnt explain really well and i need some help

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?

Solve for x and y: 217x + 131y = 913; 131x + 217y = 827

Identify the number 127 as a rational or irrational. explain