If x is x% of y, and y is y% of z, where x, y, and z are positive real numbers, what is z?
Source: Crux Mathematicorum
From the 2nd equation,
y = (y/100)*z
Since y is not allowed to be zero (the puzzle requires it to be positive), just multiply by 100/y to get z = 100. Final answer.
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Note:
If x, y and z did not need to be positive, then the (x,y,z) could be (0,0, anything) or (0, anything, 100).
But, given the puzzle conditions, (x,y,z) need to be (anything positive, 100, 100).
Edited on March 14, 2016, 4:01 pm
Quickie answer (spoiler)