25) Let A be a ring with unity and B a subring of A, For any ele- ment x E C(A), That is , x commutes with all the other elements in A, Consider the subring generated by the set AU x and denoted by (B,x) . Show that (B,x) = (bot bix + .......+ bnx" |nEZ+} 26) Let. A be a ring which does not contain a unity Consider the