The price of four new tires changes from $638 to $523.16. Find the percent of increase or decrease

To find the percent of increase or decrease, we first need to determine the amount of change.

Amount of change = new price - old price
Amount of change = $523.16 - $638
Amount of change = -$114.84 (there is a decrease)

Now we can find the percent of decrease:

Percent decrease = (amount of change / old price) x 100%
Percent decrease = (-$114.84 / $638) x 100%
Percent decrease = -0.18 x 100%
Percent decrease = -18%

Therefore, the price of the four new tires decreased by 18%.