y=mx+b
(x,y)
m= slope
b= y-intercept
slope is y2-y1/x2-x1
find your slope and then put a coordinate pair in your equation (y=mx+b) then solve to get a number for b.
Try it using the coordinates
(66,64) and (68,66)
x1 y1 x2 y2
Try it and put your answer in the comments and I will tell you if you are right!
The only way to learn is to try and get guidance, but not answers just given to you!