Ack! i need help with stuff

programming
1 
function playerattack(atktype, element) {
    hitmax = Number(_root.wephitmax);
    hitmin = Number(_root.wephitmin);
    str = Number(_root.playerstr);
    lvl = Number(_root.playerlevel);
    attackelement = _root.atkelement;
    _global.atktype = atktype;
    _global.atkelement = element;
    _global.hitdmg = random(hitmax)+0.5*(Str+Lvl/3);
    CheckResist1();
    _global.hitdmg = math.round(_global.hitdmg);
    if (_global.hitdmg<=hitmin) {
        _global.hitdmg = hitmin;
    }
    CheckResist2();
    _root.monsterhp = Number(_root.monsterhp)-Number(_global.hitdmg);
}
/// Resistances and such
/// for monsters and players
///
function CheckResist1() {
    AttackElement = _root.atkelement;
    Target = _root.atktarget
    _global.hitdmg = Number(_global.hitdmg)+_root.Target.AttackElement;
    if (_global.hitdmg <= 0) {
        Target.gotoAndPlay("block");
    }
}
///
///
///
function monattack(atktype, element, damage) {
    _root.damage = damage;
    _global.hitdmg = random(_root.damage);
    _global.atktype = atktype;
    _global.atkelement = element;
    _global.hitdmg = _global.hitdmg;
    _root.hp = Number(_root.hp)-Number(_global.hitdmg);
}
function messagebox(msg) {
    _root.txtmsg = msg;
    _root.msg.gotoAndPlay(2);
}
function Playerturn() {
    _root.rpgmove = 1;
    _root.atktarget = "monster";
}
function Monsterturn() {
    _root.rpgmove = 0;
    _root.atktarget = "player";
}

i can’t figure out how to make a Resistance system :S
i been trying for a little over a week and im stumped :S

heres the monster movieclip coding for stats

Monstername = "DemonChomper"
fire= -25
light= +25