Me find x on either one of these problems !

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?

Present age of man is 45 years, 5 years back his age was 4 times age of his son what is present age of his son?

What is the value of x in the equation7x+2y=48 when y=3