\[y = 4x + 3;\ \ \ \ y = \frac{2}{3}.\]
\[\frac{2}{3} = 4x + 3\ \ \ \ | \cdot 3\]
\[2 = 12x + 9\]
\[12x = 2 - 9\]
\[12x = - 7\]
\[x = - \frac{7}{12}.\]
\[Ответ:при\ x = - \frac{7}{12}.\]