Getting a top-left position of a tile inside a tileset
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I have a tileset(a image full of other small images). And I wanna get one of those little images called tile so I can do something with it. I know the size of each tile(they're all the same size).
I have two equations:

    x = (i % tiles_hor) * tile_h
    y = (i % tiles_ver) * tile_w
    
    x = (i % tiles_hor) * tile_w
    y =  (i / tiles_hor) * tile_w

where **i** means the index of the tile i wanna get; <br />
**tiles_hor** is the number of tiles horizontally; <br />
**tiles_ver** is the number of tiles vertically; <br />
**tile_w** and **tile_h** is the width and height of each tile inside the tileset, respectively;

The tiles receive their index sequentially, like this:

    01 02 03 04 05 
    06 07 08 09 10
    11 12 13 14 15
    16 17 18 19 20
    21 22 23 24 25

So each pair of digit it's the index of a tile inside the tileset.
Let's say I wanna get the tile 04(assuming the tiles have a 32x32 size each):
with the first equation:

x = (4 % 5) * 32 = 128. So it's x position inside the image is 128 - **WRONG! Cause it's position is 96, since we start counting from 0;** <br />
y = (4 % 5) * 32 = 0. So it's y inside the image is 0;

with the second equation: <br />
x = (4 % 5) * 32 = 128. So it's x position inside the image is 128 - **WRONG! Cause it's position is 96, since we start counting from 0;** <br />
y = (4 / 5) * 32 = 0. Here's is 0, cause we're first rounding the first expression for the closest minor number(i don't know if my expression is right. Please correct me if it's not).

Note that we're considering a perfect square tileset (in this case 5x5)

My question is:<br />
The second works for most cases(if you assume 128 is a right answer, it works for all cases). The first stop working when there's no perfect squares tileset's and with a high height.
So what am I doing wrong there?

Also, considering 128 is the right answer for the x position. How can be a equation that is letting out a really important value (tiles_ver and tile_h) can be right? What am I missing there?