If two students, Mark and Lisa, interchange their ranks in a group of 40, where Mark is 10th from the top and Lisa is 15th from the bottom, what will be Mark's new rank from the bottom after the interchange?
B is ranked 5th from the bottom in a group of 25 people. If B swaps positions with C, who is ranked 12th from the top, what will be B's new rank from the top?