Answer
(a) $9.464 * 10^{-4} m^3$
(b) $3,160L$
Work Step by Step
$(a)$
Recall that $1qt = 946.4mL$ and that $1mL = 1 cm^3$
$1qt* \dfrac{946.4mL}{1qt} * \dfrac{1cm^3}{1mL}*\dfrac{(1m)^3}{(10^2cm)^3}$
$1qt* \dfrac{946.4mL}{1qt} * \dfrac{1cm^3}{1mL}*\dfrac{1m^3}{10^{(2*3)}cm^3}$
$1qt* \dfrac{946.4mL}{1qt} * \dfrac{1cm^3}{1mL}*\dfrac{1m^3}{10^{6}cm^3}$
Cancel units:
$946.4 * 10^{-6} m^3$
Simplify:
$$9.464 * 10^{-4} m^3$$
$(b)$
Recall that $1gal = 4qt$
$835gal * \dfrac{4qt}{1gal} * \dfrac{946.4mL}{1qt} * \dfrac{1L}{10^3mL} = 3160.976L$
There are 3 significant figures in 835 gal so our answer has 3 significant figures as well.
$$3,160L$$