I do not know where to put my values of the dex and speed stat. In other words like u make str put up dmg by doing

var/dmg = rand (1,10)+usr.str - M.def.

But how do u make dex put up ur probability of hitting a monster go up when put it up?

and how do u make speed decrease the monster's probability (or player's if monster has agi) of hitting something?

Should i put the values in my attack command or wat?
I don't know, so i hope you guys could help! Thank You for any help you can give me.