foreach (object item in listBox1.SelectedItems)
{
string curItem = item.ToString();
var parts = curItem.Split(\"{}XY=, \".ToCharArray(), StringSplitOptions.Remov
You can simply extract the float from the string by using Regular Expressions:
string xCoord = Regex.Match(curItem, @"[-+]?[0-9]*\.?[0-9]+").Groups[1].Value;
After that, you can parse it to a float.
More info about regular expressions can be found here, or you could take a look at the Regex class page from MSDN.