Answer
$\frac{4y^3z-3wz}{x^2y^4}$
Work Step by Step
Rewrite the fractions to get a common denominator. $$\frac{4z}{x^2y}-\frac{3w}{xy^4}=\frac{4y^3z}{x^2y^4}-\frac{3wx}{x^2y^4}$$ Since the fractions, have the same denominator, they can be added to get $\frac{4y^3z-3wx}{x^2y^4}$
