# How do you find the slope perpendicular to 2y = 10?

The slope of any line perpendicular to $2 y = 10$ is undefined
$2 y = 10$ is a horizontal line; therefore its slope $\frac{\Delta y}{\Delta x} = 0$
for vertical line the value of $x$ does not change so $\Delta x = 0$ and any attempt to calculate the slope resulting in trying to divide by $0$.