When a situation can be modeled by a linear equation, what information do you need in order to find an equation?

The standard equation of a line is given by:
 y = mx + b
 Where,
 m: slope of the line
 b: intersection with the y axis.
 To define the linear function you need to know the value of the constants m and b
 
 You need in order to find an equation:
 Slope of the line
 Cutting point with the y axis

4should be the last one n=4