### Theory:

This is one of  the methods to find out the values.

First, the value of one unit will be found. It will be useful to find the value of the required number of units.
Example:
Consider that $$4$$ apples cost  $$₹100$$. Then what will be the cost of $$10$$ apples?

To find this first, we have to determine the cost of one apple (price per unit).

Then we can use this single quantity value to find our required quantity.

Therefore the cost of $$4$$ apples $$= ₹100$$.

Then the cost of $$1$$ apple $$= ₹$$$\frac{100}{4}$ $$= ₹$$25.

Therefore the cost of (1\) apple $$= ₹$$25.

$\mathit{Cost}\phantom{\rule{0.147em}{0ex}}\mathit{of}\phantom{\rule{0.147em}{0ex}}10\phantom{\rule{0.147em}{0ex}}\mathit{Apples}\phantom{\rule{0.147em}{0ex}}=\phantom{\rule{0.147em}{0ex}}\mathit{Cost}\phantom{\rule{0.147em}{0ex}}\mathit{of}\phantom{\rule{0.147em}{0ex}}1\phantom{\rule{0.147em}{0ex}}\mathit{Apple}\phantom{\rule{0.147em}{0ex}}×\phantom{\rule{0.147em}{0ex}}10$

That is the cost of $$10$$ apples $$=$$ 25 $$× 10$$ $$= ₹$$250.