Final answer:
The price of Chicken Parmesan will decrease by 89.24%
Step-by-step explanation:
To find the price increase percentage, we need to compare the new price to the original price. The original price of Chicken Parmesan was $11.99 and the new menu prices are 30% of the food cost. Therefore, the new price of Chicken Parmesan is $4.31 * 0.30 = $1.29. The price increase is $1.29 - $11.99 = -$10.70.
Since the price decrease is negative, we can find the percentage decrease by dividing the decrease by the original price and multiplying by 100. The percentage decrease is (-$10.70 / $11.99) * 100 = -89.24%.
Therefore, the price of Chicken Parmesan will decrease by 89.24%.