3 ms·x(-y)=x(-y+y-y)=x(-y)+xy+x(-y) Cancellation yields 0=xy+x(-y) Therefore -(xy)=x(-y)by archgoon 17y agox(-y)=x(-y+y-y)=x(-y)+xy+x(-y) Cancellation yields 0=xy+x(-y) Therefore -(xy)=x(-y)