Considering a 4 card setup mining ZEC

Equipment cost = INR 1,00,000/-

Power consumption = INR 3,000/month

ZEC earned = INR 9,000/month

Monthly earning = INR 6,000/month

considering a 12% interest on initial investment it will take 18 months for ROI if difficulty and ZEC/INR rates remain stable.

please correct if I have miscalculated anywhere.