I would like to know if zinah with 3 women equals 100 flogs or 300 and does the punishment purify you of the sin completely

The ruling of Zina differ if the act was committed with a married woman or a virgin non married woman. In the case of a married woman the penalty is much more severe than the penalty of lashing when committed with a virgin non married woman. The best way to wipe a sin away is by sincere repentance.