Thread: Problem In Function Program

Please help me guys,
I have been given an assignment

"Task:- Write a function that accept a person salary in long integer, rate of interest & return the yearly investment "

I have made a following program!

Please point out my mistake here please

Code:

#include<stdio.h>
#include<conio.h>
float inve(long,long);
float inte(long,long);
float sum(long,long);
void main(void)
{
clrscr();
long c;
long a;
long b;
printf("Enter The Monthly Salary Of A Person:");
scanf("%ld",&a);
printf("Enter The Rate Of Interest Of A Person:");
scanf("%ld",&b);
printf("\nThe Rate In A Numbers:%ld",inve(a,b));
printf("\nThe Difference Of Interest And A Salary %ld",inte(a,b));
printf("\nThe Yearly Investment Is %ld",sum(c,b));
getche();
}
float inve(long x,long y)
{
return((y/100)*x);
}
int inte(long w,long v)
{
return(w-v);
}
int sum(long q,long r)
{
return((q+r)*12));
}