Replace the last occurrence of a word in a string - C#

Question

I have a problem where I need to replace the last occurrence of a word in a string.

Situation: I am given a string which is in this format:

Answer 1

You have to do the replace manually:

int i = filePath.LastIndexOf(TnaName);
if (i >= 0)
    filePath = filePath.Substring(0, i) + filePath.Substring(i + TnaName.Length);