The general equation of direct variation is
y = kx,
where k is a constant.
To see if the given points are a direct variation, try a few points in the equation above. If you get the same value of k every time, it is direct variation. If not, then it isn't.
Let's start with x = 7, y = 11
y = kx
11 = k * 7
k = 11/7
For the first point, we get k = 11/7. For a direct variation, you must get k = 11/7 for every point you try.
Now let's try point (8, 13).
y = kx
13 = k * 8
k = 13/8
13/8 is not equal to 11/7, so since the value of k is different for different ordered pairs, it is not direct variation.
