What is the percent increase or decrease between $7.80 and $6.63?​

It is a 15% decrease.

Amount One: $7.80
Amount Two: $6.63

You’re looking for what percent of 7.80 is 6.63.

$7.80 * X = $6.63.
X = $6.63/$7.80
X = .85

So $6.63 is 85% of $7.80.

Percents are out if 100, so if you want to know what the percent difference is, subtract 85% from 100%.

100% - 85% = 15%.

As you’re going form $7.80 to $6.63, the number is getting smaller so it’s a decrease. Overall, it’s a 15% decrease from $7.80 to $6.63.