In an Inverse variation, the values of the two variables change in an opposite manner - as one value increases, the other decreases..
Given two variables x and y, the statements
y varies inversely as x,
y is inversely proportional to x.
all mean that y=kx, for some fixed nonzero real number k. The constant k is called the constant of variation or constant of proportionality.
Simple inverse variation problems consist in find a formula and verify what happen with a quantity when we change the other quantity of the problem.
Direct variation relations have the form y = kx where x and y are variables and k is a non-zero constant. When two variables are related in such a way that the ratio of their values always remains the same, the two variables are said to be in direct variation.
In simpler terms, that means if A is always twice as much as B, then they directly vary.
Above are different types of variations.