Let the rabbits be respectively

You are told

Can you use substitution to find U1? (My answer and working are in the spoiler if you wish to check but remember you're only cheating yourself if you don't bother trying)

Spoiler:

I get an answer of £5.50 which follows because we'd get

£5.50 + £7.50 + £6.70 = £13+£6.70 = £19.70