Hi, I need help differentiating this equation

y=(cos5x) (e^-5x )

This is what I tried to do....
-5 (sin5x) (e^-5x) + 5 (e^-5x) (cos5x)

-5 (sin5x) (e^-5x) ## - ## 5 (e^-5x) (cos5x)