This should do it for you...look at what I did and apply to your code.
Code:
#include <stdlib.h>
#include <stdio.h>
/*
Author: Linda
Source: Welcome program
This program is to compute the output score, and the grade earned by the student.
Date: September 21, 2011
*/
int main(void)
{
int gradeAsg1, gradeAsg2, gradeAsg3, gradeAsg4, gradeTest1, gradeTest2, gradeExam;
float score;
printf("This program is to out the computed score, and the grade earned by the student.\n");
printf("Enter Grade for assignment 1:");
scanf("%i", &gradeAsg1);
printf("Enter Grade for assignment 2:");
scanf("%i", &gradeAsg2);
printf("Enter Grade for assignment 3:");
scanf("%i", &gradeAsg3);
printf("Enter Grade for assignment 4:");
scanf("%i", &gradeAsg4);
printf("Enter Grade for Test 1:");
scanf("%i", &gradeTest1);
printf("Enter Grade for Test 2:");
scanf("%i", &gradeTest2);
printf("Enter Grade for Test 3:");
scanf("%i", &gradeExam);
float A1, A2, A3;
A1 = ((gradeAsg1+gradeAsg2+gradeAsg3+gradeAsg4)/4)*0.2;
A2 = ((gradeTest1+gradeTest2)/2)*0.4;
A3 = (gradeExam)*0.4;
score = A1 + A2 + A3;
printf("Score: %.2f\n", score);
if (score >=87 && score<=100 )
printf ("Grade: A\n");
if ( score >= 74 && score<=87 )
printf("Grade: B\n");
if ( score >= 61 && score<74 )
printf("Grade: C\n");
if( score >= 48 && score<61 )
printf ("Grade: D\n");
if ( score >= 0 && score<48)
printf("Grade: F\n");
return 0;
}