Unleaded petrol

Here is a real life starting point for a lesson starter.  It was inspired by this advert in my local petrol station:

I plan to present it like this:

Unleaded petrol at my local station costs 133.9 pence per litre.

I filled up and needed 53.27 litres.

I then used the offer in the advert and bought two bottles of drink that cost £1.79 each.

How much did I save?

How much petrol would I need to buy in order to get the drinks for free?

I could also ask pupils at what stage it is worth getting the drinks even if I don’t really want them.  Is it sensible when they are free? - definitely.  Is it worth it when they effectively cost me only 8p? - almost certainly.  Is it worth it if I only end up saving 5p?  No.

Also, assuming I do want the drinks, what is the percentage saving on the cost of the petrol if I use the offer?

Should be a brief activity.

Presentation files (SMART and PPT) available on TES.