https://www.medcalc.org/calc/odds_ratio.php

Hi Nevin, To find an odds ratio from a given probability, first express the probability as a fraction (we'll use 5/13). Subtract the numerator (5) from the denominator (13) : 13 - 5 = 8 . The answer is the number of unfavorable outcomes. Odds can then be expressed as 5 : 8 - the ratio of favorable to unfavorable outcomes.

I have provided you the link which might help you:

https://www.openanesthesia.org/odds_ratio_calculation/

http://www.statisticshowto.com/odds-ratio/

https://www.youtube.com/watch?v=ITi0SxmQTO8

https://en.wikipedia.org/wiki/Odds_ratio

Regards,

Try this

http://www.openepi.com/

thank you very much every body i will try and get back if i need further help