math..word problem
posted by M.A. .
Tom and Fred are inseparable twins. They are in a fiveperson club. How many ways can these five line up for a photo if Tom and Fred must stand together?

treat Tom and Fred as one unit, so there are only 4 to arrange
That would be 4!
But within each those, Tom and Fred could be switched.
So the total number of ways is 2(4!) = 48