Okay so first off the equation of a line is
Y=mx+b
m= the slope
b= the y intercept
The Y intercept of this line is 2 and the slope is 5/3! You know this is the slope because if you start at point a and go up 5 and to the right 3, you end up at point b.
The equation for this line would be y=5/3x+2