Question

The upper left-hand corner of a piece of paper 8 in. wide by 17 in. long is folded over to the right-hand edge. How would you fold it so as to minimize the length of the fold? In other words, how would you choose x to minimize y?

Answer 1

Where do x and y enter the picture ??

Answer 2

if you fold it it will create a right triangle. x is the base and y is the height.

Answer 3

Here is a solution to your problem, with sides 6 and 12
I suggest you print out the solution and change the constants to yours.
I suggest you are careful that your base of x, and height of y are consistent with the x and y in the solution

https://www.math.ucdavis.edu/~kouba/CalcOneDIRECTORY/maxminsol3directory/MaxMinSol3.html#SOLUTION 21