You open a small business with an initial investment of $\mathrm{\$} 90000$. The weekly running costs for the business are $\mathrm{\$} 7800$. The weekly revenue (income) from your business is $\mathrm{\$} 8800$. Determine how long will it be before you break even (when your total profit matches the amount you have invested.)

Between $2000$ and $2010$, coal and petroleum production from the fuel producing countries can be modeled by the following system of equations, where $x=0$ represents the year $2005$ :

Coal production : $y=93.2 x+3100$

Petroleum production : $y=-29.1 x+2942$

Calculate the year in which production from both forms of fuel was equal.