If the price listed is in American dollars, then the price of 6 packets of crisps would be 5.72 because the price of three packages of crisps is 2.86 so I’m guessing since it’s three packages for the price of 2 the next sale up would be six packages for the price of 4. And the price of 4 packages crisps is 5.72. I’m SO sorry if this is wrong but I hope it helps