Android Question problem with a time calculation

Sub AppStart (Args() As String)
    Dim d1 As Long = 60.5 * DateTime.TicksPerHour
    Dim d2 As Long = ConvertHHMMToMilliseconds("10:30")
    Dim d3 As Long = d1 - d2
    Log(ConvertMillisecondsToString(d3))
End Sub

Sub ConvertMillisecondsToString(t As Long) As String
    Dim hours, minutes As Int
    hours = t / DateTime.TicksPerHour
    minutes = (t Mod DateTime.TicksPerHour) / DateTime.TicksPerMinute
    Return $"$1.0{hours}:$2.0{minutes}"$
End Sub

Sub ConvertHHMMToMilliseconds (s As String) As Long
    Dim m As Matcher = Regex.Matcher("(\d+):(\d+)", s)
    m.Find
    Dim hours As Int = m.Group(1)
    Dim minutes As Int = m.Group(2)
    Return hours * DateTime.TicksPerHour + minutes * DateTime.TicksPerMinute
End Sub

Sub ConvertMillisecondsToString(t As Long) As String
    Dim hours, minutes As Int
    hours = t / DateTime.TicksPerHour
    minutes = Abs((t Mod DateTime.TicksPerHour) / DateTime.TicksPerMinute) '->  Abs ??
    Return $"$1.0{hours}:$2.0{minutes}"$
End Sub

Sub ConvertMillisecondsToString(t As Long) As String
    Dim sign As String = IIf(t < 0, "-", "")
    t = Abs(t)
    Dim hours, minutes As Int
    hours = t / DateTime.TicksPerHour
    minutes = (t Mod DateTime.TicksPerHour) / DateTime.TicksPerMinute
    Return $"${sign}$1.0{hours}:$2.0{minutes}"$
End Sub