Bogan laid out 10 maggots for her pet beetle. The beetle only ate 1 and Bogan had to throw out the rest. Later that day, she tried feeding again and the beetle ate 3. If Bogan served 20 maggots in total, how many did she attempt to feed the beetle the second time?
Bogan served a total of 
<gadget id="calculator">20</gadget>
<output>20</output>
20 maggots.
Bogan gave the beetles 10 maggots in the first feeding.
Bogan gave the beetles 20-10=
<gadget id="calculator">20-10</gadget>
<output>10</output>
10 maggots in the second feeding.

<result>10</result>