$$\left. \begin{array} { l } { 2 x + 7 = 5 C } \\ { 10 x + 5 = 10 - ( v i ) } \end{array} \right.$$
$x=-\frac{iv}{10}+\frac{1}{2}$
$C=-\frac{iv}{25}+\frac{8}{5}$
