# Video: AQA GCSE Mathematics Foundation Tier Pack 2 • Paper 2 • Question 22

Using the information that 1 gallon = 16 cups and 1 litre is approximately 4.2 cups, change 80 litres into gallons.

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### Video Transcript

Using the information that one gallon equals 16 cups and one litre is approximately 4.2 cups, change 80 litres into gallons.

We’re starting with 80 litres. Based on the given information, we’ll need to change litres into cups and then cups into gallons. One litre equals 4.2 cups. And that means that 80 litres will be equal to 80 times 4.2 cups. 80 times 4.2 equals 336. That means 80 litres equals 336 cups.

And now we need to take these 336 cups and convert them to gallons. It takes 16 cups to equal one gallon, which means one cup equals one gallon divided by 16. One cup equals one sixteenth of a gallon. And that means we’ll take our 336 cups and multiply that by one sixteenth of a gallon. 336 multiplied by one sixteenth equals 21. We’ve shown that 80 litres equals 336 cups and that 336 cups equals 21 gallons.