Output (submarines per year) 0 1 2 3 4 5 Price (millions per submarine) --- $ 90 $ 80 $ 70 $ 60 $ 50 Total Cost (millions per year) $ 10 30 70 120 190 280 Marginal Cost (millions per year) --- _________blank _________blank _________blank _________blank _________blank Total Revenue (millions per year) 0 90 160 210 240 250 Marginal Revenue (millions per year) --- _________blank _________blank _________blank _________blank _________blank Total Profit (millions per year) _________blank _________blank _________blank _________blank _________blank _________blank Refer to the table. At an output rate of 4 submarines per year, marginal revenue is equal to