1. As you can see in the figure attached, the area of the photograph is:
A=LxW
A is the area of the photograph (A=54 in²).
L is the lenght of the photograph (L=12-4x).
W is the widht of the photograph (W=12-2x)
When you substitute these values into the formula A=LxW, you obtain:
A=LxW
54=(12-4x)(12-2x)
2. Now, you must apply the distributive property. Then:
54=144-24x-48x+8x²
8x²-72x+144-54=0
3. Therefore, you obtain a quadratic equation for the area of the photo:
8x²-72x+90=0
The answer is:
8x²-72x+90=0