## Ratios and proportions:

Ratios are defined as the comparison between two quantities that relate. It is expressed as the fraction of one quantity by the other related quantity. An example of a ratio consists of given the number of students in a classroom, we could find the ratio of male students by the number of female students in the classroom. On the other hand, a proportion is defined as two ratios or rates that are equal to each other. A proportion will be true if the two ratios are equal to each other.

$$\dfrac{a}{b}=\dfrac{c}{d}$$

In order to determine Hari's income, we need to establish a proportion that will relate what he spends in rent, and what will be the total income. As we know the percentage of Hari's income that is spent on rent, we can use the ratio of money per percentage of income to determine the total income of Hari.

{eq}\dfrac{r}{40%}=\dfrac{i}{100%} {/eq}

Where:

• r is the amount of money Hari spends in rent
• i is Hari's income.

Solving for the income:

{eq}\dfrac{r}{0.40}=\dfrac{i}{1.00}\\ i=\dfrac{220}{0.40}\\ i=550 {/eq}

Hari's total income is of \$550 dollars.