3x-4 to y+15

Question

is constant and
y=3 when x=2
then when
y=12, x equals?

My answer was 13. Im not sure how to solve this question. Could you please go through the steps so I can see they match up with mines.

My Steps:

3x-y:y+15 The original problem above says 3x-4 and not 3x-y. Try it again. I have 7/3 for the answer.
3x-12:12+15
3x-12:27
-12-27:-3x
-39:-3x
13:x

I'll try again:
3x-4:y+15
3x:12+15+4
3x:31

Now what. Is what I did right?

I need help with this problem.

Given that the ratio of
3x-4 to y+15
is constant and
y=3 when x=2
then when
y=12, x equals?

My answer was 13. Im not sure how to solve this question. Could you please go through the steps so I can see they match up with mines.

My Steps:

3x-y:y+15
3x-12:12+15
3x-12:27
-12-27:-3x
-39:-3x
13:x

The problem said the ratio was a constant when x=2 and y=3
I substituted x = 2 and y=3 and solved for the constant.
(3x-4)/(y+15) = k
I found 1/9 for k.

Then I started anew, substituted y=12 and solved for x.
There may be an easier way to do it but I think this will work.

I tried that did I not. I honestly don't understand. Can you please type it out.