In an inverse variation, which values remain constant?

What about a direct variation? Which value remains constant?

Inverse proportion:

In inversely proportion, one quantity is inversely proportion to another when the product of the two quantities is constant. An inverse proportion can be described by an equation of the form xy = k, where k is called the constant of proportionality.

Direct proportion:

if y is directly proportional to x then y = kx.

Thus the ratio of y and x that is y/x = k.

Thus the ratio y/x remains constant.

in some questions, you will have to calculate the value of k first... don't say
y = 1/x

it's wrong... I've notice a few friends committing this silly mistake.
So, be careful.