Calculate the substitution and income effects for the following utility function:
$$ u(x,y)=\frac{x^a}{a}+\frac{y^a}{a}$$
I know that we are supposed to use the Slutsky equation which accounts for the substitution effect minus the income effect however I am not quite sure how to solve it. The only thing which I know how to do is derive the $x$ and I will get $x^{a-1}$ but after I am not sure what to do.