how can i?

guys how can i calculate the amount of ex i get in strenght?
like im lvl 28 ( strenght ) and i usally fight lvl 21 ( combat ) and i have a mithrill long sword and my max attack is 5 so how do I calculate the exp?

Do you mean per hit?
Every hit you do (Except on random events) you get 4 exp.
So if you hit a 5, that is 20exp.
Use this fighting calc to work out how many of a certain type of monster you need to kill to get your level up, if that is what you mean.
http://www.rsbandb.com/calc/src/calcfin2.php?skill=fighting&by=lvl&order=ASC&memb=1

sickmate 8)

your the man dude =)