$($Entry Deterrence$)$ Joe's Gas, the only gas station at a busy highway exit, earns a monopoly profit of $\backslash$$$10,000$ per week. Joe is concerned about entry. He can obtain an exclusive right that would prevent others from entering the market at this location, at a cost of $\backslash (\backslash$$ $\backslash$mathrm$\{$~b$\}\backslash )$ per week. If Joe does not buy the exclusive right, a potential entrant must decide whether to enter. If entry occurs, Joe's profit will fall to $6000$ per week and the entrant will earn $\backslash (1000-\backslash$mathrm$\{$F$\}\backslash ),$ where F is a weekly fixed cost.

Suppose $\backslash ($ F$=900\backslash )$ and $\backslash ($ b$=4,261\backslash ).$ Calculate the profits earned by the incumbent, Joe, in the sequential Nash equilibrium. Enter your answer with one digit after the decimal.