\[\boxed{\mathbf{78}.}\]
\[y = kx - 2\]
\[1)\ M( - 2;4):\]
\[4 = - 2k - 2\]
\[- 2k = 6\]
\[k = - 3.\]
\[График:\ \ y = - 3x - 2.\]
\[2)\ N(9;1):\]
\[1 = 9k - 2\]
\[9k = 3\]
\[k = \frac{1}{3}.\]
\[График:\ \ y = \frac{1}{3}x - 2.\]