Answer
$y=\pm5+13$
Work Step by Step
The distance formula from $P_1(x_1,y_1)$ to $P_2(x_2,y_2)$ is $d=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}$.
Hence here: $\sqrt{(1-8)^2+(y-13)^2}=\sqrt{74}\\49+(y-13)^2=74\\(y-13)^2=25\\y-13=\pm5\\y=\pm5+13$
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