y= 2 - (5/2) sec( (2pi/5)x-4pi)

By what factor is the graph of this secant function being stretched horizontally?

I thought you're supposed to divide 2pi by 2pi/5:

2pi/(2pi/5)=

2pi * 5/2pi =

10pi/2pi = 5

The correct answer was 2pi/5

Please help me understand this. I have a unit exam next week and a quiz I need to be studying for tomorrow.