Van Helsing gets paid by the town to remove all the vampires and werewolves. He gets $5 per vampire and $10 per werewolf. He removes half the vampires and removes 8 werewolves, and earned $105. There were 4 times as many werewolves as vampires. What percentage of the werewolves did he remove?
He earns $80 from werewolf removal because 8 x 10 = 
<gadget id="calculator">8*10</gadget>
<output>80</output>
80.
He earned $25 from vampire removal because 105 - 80 = 
<gadget id="calculator">105-80</gadget>
<output>25</output>
25.
He removed 5 vampires from town because 25 / 5 = 
<gadget id="calculator">25/5</gadget>
<output>5</output>
5.
There were 10 vampires because 5 / .5 = 10.
There were 40 werewolves because 4 x 10 = 
<gadget id="calculator">4*10</gadget>
<output>40</output>
40.
The proportion of werewolves that he removed was .2 because 8 / 40 = 
<gadget id="calculator">8/40</gadget>
<output>1/5 = around 0.2</output>
.2.
The percentage of werewolves removed was 20% because 100 x .2 = 
<gadget id="calculator">100*.2</gadget>
<output>20</output>
20.

<result>20</result>