Q&A
Show that the set D of all integers form a commutative group with respect to
show that the set D of all integers form a commutative group with respect to the composition*defined by a*b =a+b-1for all a,b in D
show that the set D of all integers form a commutative group with respect to the composition*defined by a*b =a+b-1for all a,b in D