hi please help me. Not an allowed type in Turbo C++ : So I'm trying to make a grading system. I've already made a program that does it but I just recently found at that we need to use procedures and functions, this is what I've done so far.So what i want to do is take 1/3 of the value of outputgrade and add it with 2/3 of the value of outputgrade2, I tried midterm1=(outputgrade()*1/3)+(outputgrade2*2/3) but I receive an error which is "Not an allowed type". Please somebody help me on what to do.
    



    #include<iostream.h>
    #include<conio.h>
    #include<iomanip.h>

    double AAO,Quizzes,Project,MajorExam,Midterm;


	void inputprelim()
		{
			clrscr();
			gotoxy(3,4);cout<<"Input Prelim Grade";
			gotoxy(1,6);cout<<"Attendance/Ass./Oral: ";cin>>AAO;
			gotoxy(1,7);cout<<"Project: ";cin>>Project;
			gotoxy(1,8);cout<<"Quizzes: ";cin>>Quizzes;
			gotoxy(1,9);cout<<"Major Exam: ";cin>>MajorExam;
			gotoxy(1,11);cout<<"Prelim Grade: ";
		}

	int getgrade(double a, double b, double c, double d)
		{
			double result;
			result=(a*0.10)+(b*0.20)+(c*0.30)+(d*0.40);
			cout<<setprecision(1)<<result;
			return result;
		}
	void outputgrade()
		{
			getgrade(AAO,Project,Quizzes,MajorExam);
			getch();
		}
	void inputmidterm()
		{
			gotoxy(33,4);cout<<"Input Midterm Grade";
			gotoxy(29,6);cout<<"Attendance/Ass./Oral: ";cin>>AAO;
			gotoxy(29,7);cout<<"Project: ";cin>>Project;
			gotoxy(29,8);cout<<"Quizzes: ";cin>>Quizzes;
			gotoxy(29,9);cout<<"Major Exam: ";cin>>MajorExam;
			gotoxy(29,11);cout<<"Temporary Midterm Grade: ";
			gotoxy(29,12);cout<<"Final Midterm Grade: ";
		}
	void outputgrade2()
		{
			getgrade(AAO,Project,Quizzes,MajorExam);
			getch();
		}


	void main()
		{
		inputprelim();
		gotoxy(15,11);outputgrade();
		inputmidterm();
		gotoxy(54,11);outputgrade2();
		gotoxy(55,11);
		Midterm1=(outputgrade()*1/3)+(outputgrade2()*2/3);
		}

