What percentage of 90 kg is 36 kg? One way to solve this problem is to first find what percentage 1 kg is of 90, and then multiply by 36.

From the table we can see that 1 kg is $\left(\frac{1}{90}\boldcdot 100\right) \%$, so 36 kg is $\left(\frac{36}{90}\boldcdot 100\right) \%$ or 40% of 90. We can confirm this on a double number line:

In general, to find what percentage a number $C$ is of another number $B$ is to calculate $\frac{C}{B}$ of 100%. We can find do that by multiplying: $$\frac{C}{B}\boldcdot 100 $$

Suppose a school club has raised \$88 for a project but needs a total of \$160. What percentage of its goal has the club raised?

To find what percentage \$88 is of \$160, we find $\frac {88}{160}$ of 100% or $\frac {88}{160} \boldcdot 100$, which equals $ \frac {11}{20} \boldcdot 100$ or 55. The club has raised 55% of its goal.