Question

7 ft
3 ft
12 ft
8 ft
□ ft²

Explanation:

Step1: Calculate outer - rectangle area

The area formula for a rectangle is $A = l\times w$. For the outer rectangle with length $l = 12$ ft and width $w = 8$ ft, $A_{outer}=12\times8 = 96$ $ft^{2}$.

Step2: Calculate inner - rectangle area

For the inner rectangle with length $l = 7$ ft and width $w = 3$ ft, $A_{inner}=7\times3=21$ $ft^{2}$.

Step3: Calculate the shaded area

The shaded area $A$ is the difference between the outer - rectangle area and the inner - rectangle area. So $A = A_{outer}-A_{inner}=96 - 21=75$ $ft^{2}$.

Answer:

$75$