Answer
$y=-x+8$
Work Step by Step
The point-slope form of the line is
$y-y_{1}=m(x-x_{1})$
Given: $m=-1$, $(x_{1},y_{1})=(3,5)$
Substituting the values, we get
$y-5=-1(x-3)$
$\implies y=-x+3+5$
$\implies y=-x+8$
The equation is
$y=-x+8$