Answer:
The equation of the line is 
Step-by-step explanation:
Looks like you've already found the y-intercept and slope of this graph. Great! That's all the info we need to create an equation.
The equation of a line is always in
form, where k is the constant of proportionality (aka the slope) and b is the constant added (aka the y-intercept).
We know the slope is 3 and the y-intercept is 3, so we can put these values into the equation.

Hope this helped!
A problem with extra information will be difficult to solve because you may not be able to tell what information you might need to use for the problem.
B would have to equal 9 and a should equal -2 to get 0