How to find total and percentage of marks using function?

CODE

How to find total and percentage of marks using function?

//Write a function : dototal() with 3 sunject marks as arguments and return total to main(). Then pass total from main() to function: doper(),to calculate percentage and return per to main and show on screen.

int main()

{

    float s1,s2,s3,total,per;

    printf("\n enter marks of 3 subjects(out of 100 each):");

    scanf("%f%f%f",&s1,&s2,&s3);

    float dototal(float s1,float s2,float s3);

    total=dototal(s1,s2,s3);

    float doper(float total);

    per=doper(total);

    printf("\n total=%f",total);

    printf("\n percentage=%f",per);

}

float dototal(float s1,float s2,float s3)

{

    float total=s1+s2+s3;

    return total;

}

float doper(float total)

{

    float per=total*100/300;

    return per;25194

}

Output:

enter marks of 3 subjects(out of 100 each):

87

98

100

 total=285.000000

 percentage=95.000000