We had a good collection of offers:

David from St.Albans, Adam from Ystalyfera, Adrianos, Julian from Wilson's School, and Andrei from Bucharest all sent in their chosen sets of fractions with their reasons.

Here's one set in a table : it shows, for example, that 3/4 is 15/16 of 4/5 (check that for yourself)



And here's the spreadsheet file I used to check the fraction sets which people sent in .(Excel file )

If you check some other possible solutions then you will find that Andrei has found the best set.