12 bars of soap for $10.00 or 5 for 4.00 which is better? and why?

12 bars of soap for 10$ because when you divide 12/10 you get $1.20 per bar of soap. and when you divide 5/4 you get $1.25 per bar of soap. No only is it a little cheaper but you get more soap. 

Looking at it this way too: if you do purchase 5 for $4 but you want the 12 bars of soap the other deal has, you would still be paying more. You'd be paying $10.50 for 12 bars of soap with that deal.