Let R be a nonzero commutative ring, and let T be a nonempty subset of R closed under multiplication and containing neither 0 nor divisors of 0.

Show:

a) Q(R,T) has a unity even if R doesn't

b) In Q(R,T) every nonzero element of T is a unit.

c) how many elements are there in the ring Q(Z4, {1,3})

d) describe the ring Q(3Z, {6^N | N is in Z+}) by describing a subring of R to which it is isomorphic.

Thanks