What's the percentage change in the price of spaghetti between prices of $18 and $20

the difference in the price of $18.00 and $20.00 is $2.00 which is 10%. If the price of the item is $20.00 and you reduce it by 10% will make it $18.00. Calculate this way 20-10%=18. Therefore the percentage in difference is 10%