### Theory:

A ratio is a comparison of values. In other words, 'A ratio says how much of one thing there is compared to another one'.
Example:
There are $$2$$ eggs and $$3$$ cups of flour.

Ratios can be shown in a variety of ways:
• Use "$$:$$ "to set the values as $$2$$$$:$$$$3$$.
• Or maybe we can use the word "to" as $$2$$ to $$3$$.
• Or write it down as a fraction $$\frac {2}{3}$$.
Proportion states two ratios (or fractions) are the same.
Example:

From the above picture, we can easily understand that $$\frac {2}{3}$$ $$=$$ $$\frac {4}{6}$$.

Therefore, $$2$$ eggs out of $$3$$ cups of flour is equal to $$4$$ eggs out of  $$6$$ cups of flour.

The ratios are the same. So, they are in proportion.