Jake amasses a fortune of 80 bitcoin.  He donates 20 bitcoins to charity.  He then gives half of all the bitcoins to his brother.  After that, he triples the number of bitcoins he has.  Then he donates another 10 coins.  How many coins does he have?
He had 80-20=
<gadget id="calculator">80-20</gadget>
<output>60</output>
60 after the donation.
He kept 60/2=
<gadget id="calculator">60/2</gadget>
<output>30</output>
30 after giving half to his brother.
So he has 30*3=
<gadget id="calculator">30*3</gadget>
<output>90</output>
90 coins.
He then does 1 more donation and has 90-10=
<gadget id="calculator">90-10</gadget>
<output>80</output>
80 coins left.

<result>80</result>