\[y = \frac{3}{4}x - 9\ \ \ \ и\ \ \ \ y = 3 - \frac{5}{4}x\]
\[\frac{3}{4}x - 9 = 3 - \frac{5}{4}x\]
\[2x = 12\]
\[x = 6.\]
\[y = \frac{3 \cdot 6}{4} - 9 = 4,5 - 9 = - 4,5.\]
\[Ответ:(6;\ - 4,5).\]