Neil Gammack (Letters, 11 July) asks what a graduate earning £21,001, with a debt of £50,000 a year, would have to pay every month to offset the interest on the loan. He thought it would be a huge sum, I suppose, and was angry that the Guardian refers to the student loan as a “so-called debt”. Repayments are not based on the size of the loan but on the graduate’s salary. You pay 9% of the difference between your salary and £21,000 – in this case £1 per year. One twelfth of 9% of this would be paid per month, ie less than a penny!

Trevor Randall

Bryants Bottom, Buckinghamshire

• While your report (13 July) about a “giant iceberg twice the size of Luxembourg” breaking off an Antarctic ice shelf is alarming, on a lighter note it is good to see that the Luxembourg is now a recognised unit of size along with the Wales, the Belgium, the football pitch and the double-decker bus. This may be related to Gilles Müller’s recent success at Wimbledon, though I am not sure how.

Henry Wickens

Waldbillig, Luxembourg

• An interesting image from Tom Jenkins’ infrared camera (Eyewitness: Wimbledon, 13 July): it aroused memories from 20 years ago when a note explaining exactly what we had apparently done wrong was often included with our photos back from SupaSnaps.

Richard Burtle

Laceby, Lincolnshire

• When I am walking with Maisie, my cocker spaniel, if she sees a discarded bottle or can on the grass verge, much to the amusement of my fellow dog walkers, she picks it up and takes it home (Let’s get rid of litter one piece at a time, Letters, 13 July). I haven’t yet managed to train her to put it in the recycling bin but I am working on it.

John Davies

Kirkby, North Yorkshire

• The Australians ran an anti-littering campaign including the slogan “don’t be a tosser”.

Chris Thompson

Oxford

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