point slope form
y-y1=m(x-x1)
where the point is (x1,y1) and the slope is m
the slope between the points (x1,y1) and (x2,y2) is (y2-y1)/(x2-x1)
given
(2,5) and (3,0)
slopoe=(0-5)/(3-2)=-5/1=-5
m=-5
we see we are given
y-__=__(x-2)
x1=2
the point used was (2,5)
therefor
y1=5
m=-5
y-5=-5(x-2)