13-y. 1 ————=- 17-y. 2

To solve the equation

\[ \frac{13 - y}{17 - y} = 2, \]

we can start by cross-multiplying to eliminate the fraction:

\[ 13 - y = 2(17 - y). \]

Expanding the right side:

\[ 13 - y = 34 - 2y. \]

Next, we'll isolate \( y \) by adding \( 2y \) to both sides and also subtracting 13 from both sides:

\[ -y + 2y = 34 - 13, \]

which simplifies to:

\[ y = 21. \]

So the solution to the equation is

\[ y = 21. \]