Hello, cloud5!
They "multiplied from the right".
See it?
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?