兩個數字之間的減法並在一個新的數據透視頁中顯示結果

Question

我想創建一個減法函數，用戶輸入一個收入並在不同的支點上輸入支出，然後讓它在一個單獨的總結上顯示結果，頁。

這裏是什麼，我粗略地試圖完成的截圖：

Answer 1

public class Bill 
{ 
    public string Name {get;set;} 
    public double Value {get;set;} 
} 

public class ViewModel : INotifyPropertyChanged 
{ 
    private ObservableCollection<Bill> earnings; 
    public ObservableCollection<Bill> Earnings 
    { 
     get {return earnings;} 
     set 
     { 
      if (earnings != value) 
      { 
       earnings = value; 

       if (earnings != null) 
       { 
        earnings.CollectionChanged += (s, e) => 
        { 
         NotifyPropertyChanged("Breakdown"); 
        } 
       } 
      } 
     } 
    } 

    //Outgoins the same as Earnings 

    public double Breakdown 
    {   
     get 
     { 
      Sum = 0; 

      foreach (Bill in Earnings) 
      { 
       Sum += Bill.Value; 
      } 

      foreach (Bill in Outgoins) 
      { 
       Sum -= Bill.Value; 
      } 
      return Sum; 
     } 
    } 
}