Staking formula help

[parbynat]

On my spreadsheet I have in one cell the number 6 which is the odds then in another cell I have the number 100 which represents the amount I want to win.
When I divide 100/6 it gives me 16.66 so if I stake that amount I win 100 but in reality I win 83.33.
A stake of 25 wins me 125 in total so the amount i win is 100.
I've been trying for ages to try and derive 25 from odds of 6 and the amount 100 but have failed everytime.

Can someone help with this?
Thanks

[Jukebox]

Not a surprise as you only need £20 at odds of 6 to win £100

win amount required/(odds-1)=stake required to win the win amount


for your example:
100/(6-1)=20

[parbynat]

I've had my head in this spreadsheet all day messing with ladder increments, not sure why I went down this road and now feel a bit daft.
Should have taken that afternoon nap.
Thanks for replying.