Hi nauna,
Check this example. Now please take its reference and correct your code.
C#
string timeStamp1 = "19 hours 15 min";
string timeStamp2 = "10 hours 10 min";
timeStamp1 = timeStamp1.ToLower().Replace(" hours ", ":").Replace("min", "");
timeStamp2 = timeStamp2.ToLower().Replace(" hours ", ":").Replace("min", "");
TimeSpan ts1 = TimeSpan.Parse(timeStamp1);
TimeSpan ts2 = TimeSpan.Parse(timeStamp2);
Response.Write(Math.Round(ts1.Add(ts2).TotalHours) + " hours " + ts1.Add(ts2).Minutes.ToString().PadLeft(2, '0') + " min");
VB.Net
Dim timeStamp1 As String = "19 hours 15 min"
Dim timeStamp2 As String = "10 hours 10 min"
timeStamp1 = timeStamp1.ToLower().Replace(" hours ", ":").Replace("min", "")
timeStamp2 = timeStamp2.ToLower().Replace(" hours ", ":").Replace("min", "")
Dim ts1 As TimeSpan = TimeSpan.Parse(timeStamp1)
Dim ts2 As TimeSpan = TimeSpan.Parse(timeStamp2)
Response.Write(Math.Round(ts1.Add(ts2).TotalHours) & " hours " + ts1.Add(ts2).Minutes.ToString().PadLeft(2, "0"c) & " min")
Output
29 hours 25 min
