Answer:
9 units²
Explanation:
A differential of area is ...
dA = ((2y -y²) -(y² -4y))·dy = (-2y² +6y)·dy
The indefinite integral of this will be ...
a = -2/3y³ +6/2y²
Then the definite integral over the limits [0, 3] will be ...
(-2/3·3³ +3·3²) - 0 = 9 . . . . square units