#### Answer

$5ba^{3} - 5ab $

#### Work Step by Step

We simplify the parenthesis
$ab^{2} + ba^{3} + 4a^{3}b - ab^{2} - 5ab $
Rewrite the terms so that terms with the same variables and powers are written together
$4a^{3}b + ba^{3} + ab^{2} - ab^{2} - 5ab $
$5ba^{3} - 5ab $