I've came across an example...

By using A-B=A n B', prove that (A u B)-(A n B)=[A-(A n B)] u [B-(A n B)]

The solution they gave is...

(A u B)-(A n B)=(A u B) n (A n B)'

=[A n (A n B)'] u [B n (A n B)'] <---Distributive Law

=[A-(A n B)] u [B-(A n B)]

What I wanna know is what happen at the 2nd step? How to a that by using distributive law?