slope intercept form
y=mx+b
where the slope is m and b is the y intercept
the slope is needed
slope between (x₁,y₁) and (x₂,y₂) is (y₂-y₁)/(x₂-x₁)
so,
given (4,5) and (8,9)
the slope is (9-5)/(8-4)=4/4=1
y=1x+b
find b
input a point
(4,5)
x=4 and y=5
5=1(4)+b
5=4+b
minus 4 both sides
1=b
y=1x+1 is slope intercept form
