Original: $85

New: $90

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, 85 as the base.

The percent proportion is

To solve for r, first find the cross products.

                                       (Multiply: )

                        (Divide each side by 85)

                                            (Cancel common terms)

                                 (Divide: )

The percentage of increase by .

The percent of change is a percent of increase.The percentage of increase by .