请问这个这个程序结果是40还是37~请求解释~谢了

#include <iostream>
using namespace std;
class Test
{
   public:
   static int x;
   Test (int i=0)
   {
       x=i+x;
   }
   int Getnum()
   {
       return Test::x+7;
   }
};
   int Test::x=30;
   void main()
   {
       Test test;
   cout<<test.Getnum()<<endl;
   }