A particular copper ore deposit has a mill head grade of $0\mathrm{.}9\%$ Cu$.$ The recovery is expected to be $85\%.$

Determine the net value of the produced ore considering the following information:

Cost of mining $-$ Rs$.560$ per ton, Cost of processing $-$ Rs$.680$ per ton, General and administrative costs $-$ Rs$.220$ per ton, Depreciation $-$ Rs$.170$ per ton, Freight, smelting, and refining $-$ Rs$.450$ per

ton, Value of copper $=$ Rs$.410$ per kg$.$ What will be the cutoff grade for this case?