Apps grades calculator

[thikn]

Hello guys, yet another newbie here...
I want to build an app that calculate the grade that someone from my university needs to score not to fail the semester.
Sorry for my monkey english.
The thing is, all I have is this c++ code I've made.. I don't know anything about development. Today I downloaded SDK and NDK but I don't know what to do with these LOL. Here goes the code.

#include<stdio.h>
#include<conio.h>
#include <cstdlib>
#include <iostream>
using namespace std;
int main()
{
   float a,b,gradetest2;
   printf ("INSERT YOUR FACTOR\n");
   scanf ("%f",& a);
   printf ("INSERT YOUR GRADE ON TEST 1\n");
   scanf ("%f",& b);
   gradetest2=((4.95) - (b*0.4*a))/(0.6*a);
   cout<<"You need "<<gradetest2<<" not to fail"<<endl;
      if (gradetest2 <=3)
         {
            printf ("YOU CAN PARTY");
            getch();
         }
   else
          {
               printf ("STUDY HARD, BITCH");
                getch();
           }
   system("pause");
   return EXIT_SUCCESS;
   }

Yes, it works.
Can anybody help me?
Thanks in advance!


just so you know it, 'factor' is something that will multiply your grades.. it goes from 0.8 to 1.1