Write an equation in slope-intercept form for the line that passes through (5, 4) and is Perpendicular to the line Y = x – 5.

If it is perpendicular to the line $y=x-5$, it means the line's slope must be $-1$, hence $y=-x+c$ for some c. plugging in $(5, 4)$ gives $4=-(5)+c, 9=c$, so the equation for the line is $\boxed{y=-x+9}$