solve for y. -2x+3y=9
whats the parallel line equation?
whats the perpendicular line?
$\displaystyle 3y = 9 + 2x \Rightarrow y = \frac{9 + 2x}{3}$.
Once you have solved for y, gradient = coefficient of x.
Parallel lines have the same gradient.
The product of the gradients of a pair of perpendicular lines is equal to -1.
Without further data, the best you can do is express the equation of each required line in the form y = mx + c where m is the gradient (which you can calculate) and c is the y-intercept (for which there is not enough data to get a value of).