since this point is exactly the middle point of the rectangle, we know that the full diagonal is 26, but since they are asking information until the midpoint, WR=13.
after equal the equation to 13
[tex]\begin{gathered} 13=3y+4 \\ 13-4=3y \\ 9=3y \\ y=\frac{9}{3} \\ \\ y=3 \end{gathered}[/tex]
