9514 1404 393
Answer:
50%
Explanation:
After a reduction by 33 1/3%, the price is 66 2/3% = 2/3 of its original value. To bring it back to 1 times the original value, it must be multiplied by the reciprocal of 2/3, that is, it must be multiplied by 3/2 = 1.50 = 1 +50%.
The price must be increased by 50% to bring it back up to $540.