Answer:
y = 3x
Step-by-step explanation:
This is dealing with slope so think of it as rise over run
[tex]\frac{Rise}{Run}[/tex]
The y intercept is a 0 so you don't have to worry about adding a number after the plus symbol. You can if you want but that's not an option. You go up 3 over 1 and then you get to your next point.
