I’m sorry if I’m wrong but I do think your answer is X=22y^-1
Annually cumulating interest can be determined by the following formula:

r represents the interest rate as a decimal, and P represents the starting amount of money.
Pythagorean theorem.
a^2+b^2=c^2
This means that the square of the length of the 2 legs of a right triangle added together = the square of the length of the hypotenuses or diagonal.
If you know 2 of the values in the 3 variables a,b,c what would you do to find the missing variable value?
I will not write the exact answers to this problem. I think you can figure how to write it out yourselves.