### Theory:

Here comes the list of properties on ratios:
1. A ratio is a number. It has no unit.

2. The two quantities of the ratio should be of the same unit.
Example:
The ratio of $$10km$$ to $$100m$$. Here we should not directly compare the quantities $$10km$$ and $$100m$$. Let us convert to the same unit and compare the numbers. $$10km = 10000m$$. Thus, $$10000 :100$$. In simpler form, $$100:1$$.

3. Each number of the ratio is called a term.
Example:
There are $$13$$ boys, and $$23$$ girls in class $$6$$ went on an educational trip. The ratio of boys to girls went on an educational trip is $$13:23$$. $$13$$ and $$23$$ are the terms of the ratio.

4. Order of the terms in a ratio cannot be reversed.
Example:
The ratio of the number of days in a week to the number of months in a year. The number of days in a week is $$7$$. The number of months in a year is $$12$$. The required ratio is $$7:12$$. The same information should not be taken as $$12:7$$. So $$7:12$$ is not same as $$12:7$$.