Answer
$= \frac{2a^{4}b^{3}}{5} $
Work Step by Step
$\frac{a^{3}b^{4}}{10c} \times \frac{4ac}{b}$
$= \frac{a^{3}b^{4}(4ac)}{10c(b)} $
$= \frac{4a^{4}b^{4}c}{10bc} $
$= \frac{2a^{4}b^{4}c}{5bc} $
$= \frac{bc(2a^{4}b^{3})}{bc(5)} $
$= \frac{2a^{4}b^{3}}{5} $
