How would solve for 2x - 17y = 13 for y

2x - 17y = 13

Since we don't have the the value of x we would set x = 0

2 (0) - 17y = 13

And solve

-17y = 13

y = - 13/17

You would do the same if you're solving for x

2x - 17 (0) = 13

2x = 13

x = 13/2

(I'm not sure if you are missing anything but based on the information provided this is how I would solve it.)