Answer
a) $24$
b) $24$
c) $24$
Work Step by Step
a)
$\int_0^{6}4(-\frac{1}{3}x+2)dx$ = $(-\frac{2}{3}x+8x)|_0^6$ = $24$
b)
$\int_0^{4}(\frac{1}{2})(2)(6)dy$ = $6y|_0^4$ = $24$
c)
$\int_0^{2}4(-3)(z-2)dz$ = $(-6z^{2}+24z)|_0^2$ = $24$