In an effort to capture the large jet market, Wright Brothers Aviation invested $$26$ billion developing its $1903A,$ which is capable of carrying $800$ passengers. The plane has a list price of $$310$ million. In discussing the plane, Wright Brothers Aviation stated that the company would break even when $3101903$ As were sold.

a$.$ Assuming the break$-$even sales figure given is the accounting break$-$even, what is the cash flow per plane? $($Enter your answer in dollars, not millions of dollars, and round your answer to the nearest whole number, e$.$g$.,1,234,567.)$

b$.$ Wright Brothers Aviation promised its shareholders a return of $25$ percent on the investment. If sales of the plane continue in perpetuity, how many planes must the company sell per year to deliver on this promise? $($Do not round intermediate calculations and round your answer to $2$ decimal places, e$.$g$.,32\mathrm{.}16.)$

c$.$ Suppose instead that the sales of the $1903$A last for only $10$ years. How many planes must Wright Brothers Aviation sell per year to deliver the same rate of return? $($Do not round intermediate calculations and round your answer to $2$ decimal places, e$.$g$.,32\mathrm{.}16.)$