This confused me when I first encountered it, too. Let's think about it.
First, the equation is...
y = 1/3x + 5
Our dependent variable, sometimes called the range or the output, depends on the value we give x, our independent variable or domain or input.
My mom's recipe for spaghetti sauce calls for 5 teaspoons of garlic plus 1/3-teaspoon for each can of tomato paste. If I use 2 cans of tomato paste, I put in 5 2/3 teaspoons of garlic.
y = mx + b
m is our slope, change in y over change in x, or rise/run.
b is the y-intercept, where our graph crosses the y-axis.
So, our given point is (0.5), or 5 on the y-axis. 1/3 is our slope. Go up 1 to (0,6) and right 3 to (3,6). We've moved in a positive direction both vertically and horizontally.
Does (3,6) still fit our equation?? 1/3(3) + 5 = 6, so yes.
Go up 1 from (3,6) to (3,7) and right 3 to (6,7).
1/3(6) + 5 = 7, so yeppers.
Keep going.
We can also go the other direction. A negative over a negative is a positive fraction, so -1/-3 = 1/3, right? This allows us to go from (6,7) back to (3,6) or even to (0,5). From (0,5), we can go down 1 and left 3 to (-3,4).
1/3(-3) + 5 = 4. Sure enough.
If you don't end up with a straight line, and/or if your point doesn't make the equation true, try again.
Hope this helps!
