Solving Pair of Equations This is an problem I came up on some website or another...
" Two perpendicular lines are represented by the equations $2x - 3y = 6$ and $6x + ky = 4$. What is the value of $k$? TOSS-UP"
Any help? $3$ variables, $2$ equations?? No idea how to solve.
I tried elimination by getting to $ky + 9y = -14$, and then $k(y+9) = - 14$, and then $-14/(y+9) = k$, but I don't know how to do this. 

Equation of line y = mx + c
Where m is slope of line.

Line 1-

$2x-3y=6$
$3y=2x-6$
$y=\frac{2}{3}x-2$
So slope $m_{1}$ = $\frac{2}{3}$

Line 2-

$6x+ky=4$
$ky=-6x+4$
$y=\frac{-6}{k}x+\frac{4}{k}$
So slope $m_{2}$ = $\frac{-6}{k}$

Two lines are perpendicular so $m_{1} \times m_{2}$ = -1

$\frac{2}{3} \times \frac{-6}{k}$ = -1
k = 4
