Curso de C++/Subprogramação

#include <iostream>
int main ()
{
int a, b, c,nt;
float s;
a=2; s=0; nt=0; b=0;
for (nt=1; nt<=1; nt++)
{s=s+a+b;
b= a+7
a=b
b= a+1
}
system ("pause")