Answer
$\dfrac{128}{15}$
Work Step by Step
Consider
$I= \iint_{R} f(x,y) dA$
or, $= \int_{0}^{2} \int_{0}^{4-x^2} (4-x^2-y) dy dx$
or, $= \int_{0}^{2}[4y-\dfrac{y^2}{2}- x^2y]_0^{4-x^2} dx$
or, $=\int_{0}^{2} (8-4x^2+\dfrac{x^4}{2}) dx$
Thus, we have $I=\dfrac{32}{10} -\dfrac{32}{3}+16-0=\dfrac{128}{15}$