Thank you. Let Phi: R rightarrow S be a surjective homomorphism from the ring R to the ring S. Prove that if T is a subring of R, then the set W= {b S such that b = Phi(c) for some c T} is a subring of S. [Be specific of how and where you use that T is a subring of R.] Solution for this we only have to prove that there exist identity if b is in W then tere is a element -b in W such that b - b = 0 so if phi(c) = b then phi(-c) = -b where c and -c are in T since T is a subring since phi is homeomorphism. now if b and c are in W then there are d and f in T such that phi ( d) =b and phi (f) = c then phi (df) = phi(d) phi(f) = bc in W so W is a ring and since it is subset of S so it is subring of S .