Jay walks 2 1/4 miles which if you double it so the denominators are e same for both 2 1/4 and 1 1/8 then your answer will be 18/8 (Jay) and 9/8 (Reggie). Meaning that Reggie walks have the distance Jay walks.
Suppose first that is a normal subgroup. Then by definition we must have for all , for every . Let and choose (). By hypothesis we have , i.e. for some , thus . So we have . You can prove in the same way.
Suppose for all . Let , we have to prove for every . So, let . We have that for some (by the hypothesis). hence we have . Because was chosen arbitrarily we have the desired
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