Answer:
8x+16 ft^2
Step-by-step explanation:
First we find the total area of the large rectangle
A = l*w
A = (x+3) * (x+5)
FOIL
A = x^2 +5x+3x+15
A = x^2 +8x+15
Now we find the area of the inner rectangle
A = lw
A = (x+1) (x-1)
FOIL
A = x^2 -x+x -1
A = x^2 -1
To find the shaded area, take the large rectangle and subtract the small rectangle
x^2 +8x+15 - (x^2 -1)
Distribute the minus sign
x^2 +8x+15 - x^2 +1
Combine like terms
8x+16
