Answer: rises; your slope is positive
Every single time your slope is positive, your line goes upward.
Every time your slope is negative, however, your line goes downward.
Rearrange 9x - 27y = 81 to -27y = -9x + 81 because we want to put our equation into slope intercept so that we can eventually get our 'y' all by itself.
Divide by -27 for every variable.
Your slope intercept form should now look like this; y = 1/3x - 3
Now that we're completely done or that we have 'y' by itself, it's safe to say that our answer is 1/3, which is, also, positive.
Hope this helps, dawg.