Y = Mx + b
M is the slope and can be calculate by rise/run.
M = 1 (by taking any of the two points and taking the rise as the difference in the y values of the point and the run as the difference in the c values)
If you graph them real quick you will find that the line intersects with the Yaxis at 4 so our b value is 4.
Y=mx + b
y= 1 x + 4
Y= x+4