# lambda calculus – Beta reduction of \$SS(SK)\$

I want to $$beta$$ reduce the expression $$SS(SK)$$, where

$$S = (lambda x y z. z (y x)) y x z$$

$$K = lambda x y.x$$

I have found out that the expression $$S$$ can be $$beta$$ – reduced to $$z (x y)$$

I don’t want to just replace the actual $$S$$ expression in the $$SS(SK)$$ as it would be huge, so I would like to know if I can directly introduce the beta reduction of $$S$$ within the expression $$SS(SK)$$