$93.60 x 0.2 = $18.72
$93.60 + $18.72 = $112.32 = Price before 20% discount.
$112.32 ÷ 100 x 30 = $33. 696 = Discount of 30%
$112.32 - $33.696 = $78.624 = Original Price
Therefore, the store paid $78.624 for the clarinet before the 30% markup and 20% discount.
It's just a process of working backwards.
Hope this helps :))