$$\left. \begin{array} { l } { v = 800 x _ { 1 } + 900 x _ { 2 } } \\ { t : 2 x _ { 1 } + 4 x _ { 2 } \leq 30 } \end{array} \right.$$
$x_{2}=\frac{v-800x_{1}}{900}$
$v\leq -\frac{225tx_{1}}{2}+800x_{1}+6750$
