Question:

Which deal costs less per liter?

$32 for 4 liters

OR

$8.50 for 1 liter

How I solved this problem:

I know for the first deal that 4 liters is $32, but how much does it cost for 4 liters of the second deal. To work this out I times 8.50 by 4. The answer is $34 so the first deal costs less per litre.