Easy
the easiest way is to imagine that you have a rectangle with a corner cut off
the area of the figure=area of rectangle-area cut off
area that was cut off was a triangle
area of rectangle=length times width
area of triangle=1/2base times height
so we draw imaginary lines like in attachment
find area of rectangle
legnth=9 inch
width=9 inch
area=9 times 9=81 in^2
triangle
the top part is ?+5=9, so the base of triangle=4
the side is ?+4=9, so the base is 5
area=1/2 times 4 times 5=10 in^2
area=rectangle-triangle
area=81-10=71 in^2
72/6 = 12
The awnser is x = 12
-9 is a rattional number because it is an integer and it can be squared.