Answer:
y = 12
Explanation:
The segments are equal in length, SR = TR, so set up an equation:

Multiply by 12.

Factor out the y on the left side.

There are two solutions: y = 0 and y = 12. The y = 0 solution makes no sence (segment SR can't have a length of 0). The other solution, y = 12, works just fine.