EquationGenerator.EqFormat C# (CSharp) Method

    private void EqFormat(int temp,string op)
    {
        switch(displayMode){
            case 0: //arithmetic
                switch(op){
                    case "+":
                        if((solution - temp)<0){
                            temp = Random.Range(0,solution);
                        }
                        equation = (solution-temp) + " + " + temp + " = ?";
                        break;
                    case "-":
                        equation = (temp+solution) + " - " + temp + " = ?";
                        break;
                    case "x":
                        while(true){
                            if(solution%temp==0) break;
                            temp = Random.Range(1,9);
                        }
                        equation = (solution/temp) + " * " + temp + " = ?";
                        break;
                    case "/":
                        equation = (temp*solution) + " / " + temp + " = ?";
                        break;
                    default: //wtf
                        break;
                }
                break;
            case 1: //algebra
                switch(op){
                    case "+":
                        equation = " ?  + " + temp + " = " + (solution+temp);
                        break;
                    case "-":
                        if(solution >= temp){
                            equation = "? - " + temp + " = " + (solution-temp);
                        }
                        else{
                            equation = temp + " - ? = " + (temp-solution);
                        }
                        break;
                    case "x":
                        if(temp<1) temp = (int)Random.Range(1,9);
                        switch((int)Random.Range(0,2)){
                            case 0:
                                equation = temp + " * ? = " + (temp*solution);
                                break;
                            case 1:
                            case 2:
                                equation = "? * " + temp + " = " + (temp*solution);
                                break;
                            default:
                                break;
                        }
                        break;
                    case "/":
                        equation = (temp*solution) + " / ? = " + temp;
                        break;
                    default: //wtf
                        break;
                }
                break;
            case 2: //mixed
                displayMode = Random.Range(0,2);
                EqFormat(temp,op);
                break;
            default: //wtf
                break;
        }
    }