Deleting the current line and Editing Previous line in file using python

I had scenario where I have to delete the current line if I Have ';' at the end of current line and replace string in the previous line in the text file. Here is an example:
Prev line - I am Manish &
current Line - I went to college ;
Now I have to delete the current line as it has a ';' and replace '&' with ';' in the previous line.