Well we really need to find the area of 3 polygons. The 2 triangles and the rectangle. Notice the triangles are equal. So triangle area is 1/2*base*height. But we have 2 triangles so
2 * 1/2 * base * heighg
2 and 1/2 cancel so
Area of 2 triangles =base * height
area = 12 * 9
A = 108
Now area of rectangle is length *width so
a = 9 * 7
A = 63
So to get total Are we add the all the single areas and get
A = 63 + 108
a = 171
