How do I determine which is y=-1/3x+2?

Step-by-step explanation:
This is a linear equation in slope intercept form which is
[tex]y = mx + b[/tex]
where m is the slope and b is the y intercept.
The equation
[tex]y = - \frac{1}{3} x + 2[/tex]
Has a slope of -1/3 so this means that the slope will be decreasing. A negative linear equation increases as we go left. and decreases as we go right. The y intercept is 2. So this means the graph must pass through (0,2) and when x=0, y must be 2.
In other words, look for a line that the y values increase as we go left and decrease we go right. Also look for a point (0,2) and make sure the graph pass through it.