Finn watches 11 tadpoles swimming in the pond.  Suddenly he sees 6 of them come out of hiding from under a lily pad ,then he sees 2 of them hide under a rock.  How many tadpoles can Finn see in the pond now?
When the hidden tadpoles come out, Finn sees 11 + 6 = 
<gadget id="calculator">11+6</gadget>
<output>17</output>
17 tadpoles swimming.
After some of them hide under a rock, he now sees 17 - 2 = 
<gadget id="calculator">17-2</gadget>
<output>15</output>
15 tadpoles swimming.

<result>15</result>