Determine whether each percent of change is a percent of increase or a percent of decrease. Then find the percent of change.

$\begin{array}{l}\mathrm{Original}:66\\ \mathrm{New}:30\end{array}$

The percent change is the increase or decrease in the value of a quantity. If the new value is larger than the original value then it is a percent increase and if the change in value is lesser than the original value it is called percentage decrease.

For example, if a person has 25 dollars and he gets 3 more dollars and now has 28 dollars, its percentage increase is calculated as shown:

$\begin{array}{l}\text{Increase}=28-25=3\\ \%\text{change=r,then}\\ \frac{3}{25}=\frac{r}{100}\\ r=\frac{3}{25}\times 100\\ =12\%\end{array}$

Since the new amount is smaller than the original amount, there is a percent of decrease.

We are given that

Original:66

new: 30

This is a percent of decrease because the new amount is less than the original.

$\begin{array}{l}\text{Decrease}=66-30=36\\ \%\text{change=r,then}\end{array}$

$\begin{array}{l}\frac{36}{66}=\frac{r}{100}\\ r=\frac{36}{66}\times 100\end{array}$

$\begin{array}{l}\text{r=\%change=0.5454}\times 100\\ \text{\%change=54.54}\\ \approx \text{55\%}\end{array}$

Rounding answer off to the nearest whole number, the percentage change is 55%

We find the amount of change. And calculate the percentage change as follows:

Rounding answer off to the nearest whole number, percentage change is