Original:

New:

Since the new amount is greater than the original, this is a percent of increase.

The amount of change = New Amount – Original Amount.

The amount of change = .

Let r be the percentage of increase.

Use the original number, 72 as the base.

The percent proportion is

To solve for r, first find the cross products.

                              (Multiply: )

                             (Divide each side by 72)

                                                   (Cancel common terms)

                                            (Divide: )

The percentage of decrease by 50%.

The percent of change is a percent of decrease.The percentage of decrease by 50%.