I think I've almost got it now.
Many thanks for the drawing - it makes it clear.

But ... since Derrick (starting with 50 BTC) makes 2 transactions, why there is only one change?
Is this wrong?
Derrick sends 25 BTC to Gloria - and will get 25 BTC change.
Derrick sends 15 BTC to Rustie - and will get 10 BTC change.

Thanks, unfortunately I still don't understand how it works.

I thought there are 5 UTXO ...

1) Rustie creates one output of 50 BTC which belongs to Derrick (UTXO 1) and another output of 50 BTC as change to himself (UTXO 2).
2) Derrick creates one output of 25 BTC which belongs to Gloria (UTXO 3), one output of 15 BTC to Rustie (UTXO 4) and another one of 10 BTC as change to himself (UTXO 5).

Hi there,

Can someone please explain the UTXO logic - why is 4 the result?

Rustie has 100 bitcoins stored in one UTXO. Derrick and Gloria both have 0 bitcoins. Rustie sends 50 to Derrick, who then sends 25 to Gloria and 15 back to Rustie. How many unique (spendable) UTXOs are left?

Thanks in advance,
Selter