Final answer:
To calculate the percentage decrease, subtract the new price from the original, divide the difference by the original price, and multiply by 100. For an item that decreased from $90 to $63, the price decreased by 30%.
Step-by-step explanation:
To find the percentage decrease of the item's price, you will subtract the new price from the original price, then divide by the original price and multiply by 100 to find the percentage. The formula is: (Original Price - New Price) / Original Price x 100.
Using this formula, we subtract the new price ($63) from the original price ($90): $90 - $63 = $27. Then we divide $27 by the original price: $27 / $90 = 0.3. Finally, we multiply by 100 to get the percentage: 0.3 x 100 = 30%. So the price decreased by 30%.