Show and tell all properties :
`( a ) x times ( y times z ) = ( x times y ) times z `
( b ) `x times ( y + z ) = ( x times y ) + ( x times z ) `
( c ) `( x + y ) times z = ( x times z ) + ( y times z )`
( d ) `x times ( y - z ) = ( x times y ) - ( x times z )`