I am making a mini game similar to many facebook games where you click a button a number of times and a bar fills up, where at the end, you get a prize and complete that level of mastery. UPDATE: the progress gets past bronze, but silver goes over 100%. Can someone come to my aid?

    public Texture2D _barTexture;
public Texture2D _barBorder;
public int _fullbar;
public int _adjust;
private int Mastery;
private int mBronze=10;
private string Bronze;
private int mSilver=8;
private string Silver;
private int mGold=5;
private string Gold;
private int mPlatinum=4;
private string Platinum;
private string Level;
private float fillProgress;
private bool showButton;


// Use this for initialization
void Start () {
    Mastery=mBronze;
    showButton=true;

}

// Update is called once per frame
void Update () {

}

void OnGUI(){
GUI.DrawTexture(new Rect(45, Screen.height- 165,314,36), _barBorder);   
if(GUI.Button(new Rect(361, Screen.height-165,85,36),"Do Exercise") && showButton==true){

AdjustBar(Mastery);
    }  
GUI.Label (new Rect (45, Screen.height-130, 300, 50), "Percentage:" +fillProgress);
GUI.Label (new Rect (145, Screen.height-130, 300, 50), "Mastery:" +Level);
GUI.BeginGroup(new Rect(55, Screen.height- 155, _adjust, 15));
GUI.DrawTexture(new Rect(0,0,290,15), _barTexture);     

GUI.EndGroup();     
}

int AdjustBar(int adj){
    CalculateMastery(Mastery);
    _adjust+=adj*3;
    fillProgress+= Mastery;

    if(fillProgress==100){

    Mastery=Mastery-2;
    fillProgress=0;
    _adjust=0;

    }

return _adjust; }

string CalculateMastery(int Mastery){ if (Mastery==10) Level="Bronze"; else if (Mastery==8) Level="Silver"; else if(Mastery==5) Level="Gold"; else if(Mastery==4) Level="Platinum"; return Level; } }