Let Meqdd be a Turing machine that decides EQdfa. Translate the regular expression R into a DFA D2. Run Meqdd on D and D2. Run M on w. If M stops either accepting or rejecting w, then accept.
M stops on input w.
M is a decider, i.e. M stops for all inputs. If x w then accept. If M ever stops accepting or rejecting w, then accept x.