# Direct Variation Calculator

Direct variation calculator helps to solve for variables which are directly proportional to each other. If two quantities are directly proportional, the increase in one quantity will result in increase in the other quantity.

If two quantities (x and y) are directly proportional to each other, then, they are represented as follows:

x ∝ y

If a proportionality constant is put, the above form becomes-

x = k y

Or, x/y = k

Here, “k” is the constant of proportionality. This equation represents that when two directly proportional quantities are divided, the resultant value is always a constant.

### Example of Direct Variation Calculator

Question: If the cost of 10 pens are Rs. 100, calculate the cost of 30 pens.

Solution:

Here, the cost of pens ∝ total number of pens.

Thus, the cost of pens/total number of pens = constant

Now, let the cost of 30 pens be Rs. “x”

Consider the first case,

10 pens cost = Rs. 100 and

30 pens cost = Rs. x

So, 10/ 100 = 30/x

Or, x = 300.