If you buy 2 packs of 500 mL milk, it will cost $2.50. If you buy them individually, they will cost $1.30 each. How much is your total savings from buying ten sets of 2 packs of 500 mL milk? Let's think first. Chain of thought:
The price per 500 mL milk from the 2 packs is $2.50 / 2 = $1.25. This means that for each pack of 500 mL milk, you can save $1.30 - $1.25 = $0.05. Ten sets of 2 packs mean 10 x 2 = 20 packs of 500 mL of milk. So, your total savings will be $0.05 x 20 = $1.
Therefore, the answer is 1.