Please do it very fast

The table below displays the production quantity, marginal private benefit (which equals the marginal social benefit), the marginal private cost, and the marginal social cost for producing plastic bags. If the government is trying to achieve the socially efficient level of production, what is the optimal tax in this scenario? Production Quantity MSB=MPB MPC MSC $90 $30 $60 2 80 35 65 3 70 40 70 4 60 45 75 50 50 80 6 40 55 85 7 30 60 90 O $70 O $40 O $50 O $30