Answer:
7£
Explanation:
Shamus buys 2 adult tickets which are 24£, 3 children tickets which are 21£, and 1 senior ticket which is 8£. 24 + 21 + 8 is 53. If Shamus pays with three 20£ notes, he payed 60£ in total. Shamus only needs 53£ however. 60 - 53 is 7 so Shamus would get 7£ back as change.