# How do you differentiate ((9y^2)(-2y^2))/(7y^4)?

$\frac{\left(9 {y}^{2}\right) \left(- 1 {y}^{2}\right)}{7 {y}^{4}}$
$= \frac{- 18 {y}^{4}}{7 {y}^{4}}$
$= - \frac{18}{7}$
The derivative of any constant is $0$