Provide your best answer for the following math problem. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The problem is: the product of x and y is a constant . if the value of x is increased by 80 % , by what percentage must the value of y be decreased ?
44.44 %
The percentage by which y must be decreased is approximately 54.55%.