$2.$ Petes hot$-$dog factory has a fixed cost of R$500$ per month and each unit $($hot$-$dog$)$ has avariable production cost of R$1\mathrm{.}70.$ Each unit sells for R$2\mathrm{.}50.$ Calculate:$2\mathrm{.}1$ Break$-$even volume per month. $(4)2\mathrm{.}2$ The total profit $($or loss$)$ made per month when the $450$ units are sold. $(5)2\mathrm{.}3$ The increase in profits if the monthly sales of $1000$ units is increased by $12\%.(7)$