To find the percent of change, we need to calculate the difference between the original price and the new price, and then divide this difference by the original price and multiply by 100%.
The difference between the original price of $20 and the new price of $55 is $55 - $20 = $35.
The percent of change is: ($35/$20) * 100% = 1.75 * 100% = 175%
Since the new price is higher than the original price, this is an increase. Therefore, the percent of change is a 175% increase. The correct answer is therefore
O 175% increase.