Roman the Tavernmaster has $20 worth of gold coins. He sells 3 gold coins to Dorothy. After she pays him, he has $12. How many gold coins does Roman have left?
Dorothy paid $12 for 3 gold coins so each gold coin is worth $12/3 = $
<gadget id="calculator">12/3</gadget>
<output>4</output>
4.
The Tavern master originally had $20 worth of gold coins which is $20/$4 = 
<gadget id="calculator">20/4</gadget>
<output>5</output>
5 gold coins.
He gave 3 out of 5 gold coins to Dorothy so he now has 5-3 = 
<gadget id="calculator">5-3</gadget>
<output>2</output>
2 gold coins left.

<result>2</result>