The full price is $82, (100%), the discounted price is $65.60, (?%)
So lets see something:
$82 ------------- 100%
$65.60 --------------- x%
Multiply in cross
82.x = 65,60 . 100
82x = 6560
Divide both sides by 82
82x/82 = 6560/82
x = 80
So the discounted price is equal to 80% of the initial price
100% - 80% = 20% so the discount is 20%
