Answer:
x^2 +3x
Explanation:
The outer rectangle has an area of
A = l*w = (4x)*(x+2) = 4x^2 +8x
The inner rectangle has an area of
A = (3x+5)*x = 3x^2 +5x
Subtract the inner rectangle from the outer rectangle
Shaded area = 4x^2 +8x - ( 3x^2 +5x)
Distribute the minus sign
=4x^2 +8x - 3x^2 -5x
Combine like terms
= x^2 +3x