Following are some illustrative numbers for benefits and costs arising from a program to restrict emissions of a pollutant. Current emissions are 10 tons per month. Identify the emission level at which net benefits would be maximized. Show that this is not the same as the emission level that gives the highest benefit?cost ratio. Explain the discrepancy.

Emissions (tons/month) Benefits ($ mil) Costs ($ mil) 10 9 8 7 6 0 8 18 32 0 6 42 2 00 + 4 5 432 44 54 62 68 72 74 9 14 21 36 48 64 86 10