The little squirrel mother picks pine nuts. You can collect 27 per day on sunny days and 18 per day on rainy days. It picked a total of 288 pine nuts for several days, with an average of 24 per day. How many days are there rainy days?
小松鼠妈妈采松子．晴天每天可以采27个，雨天每天可采18个．它一连几天共采288个松子，平均每天采24个，这些天中有几天雨天？
<gadget id="calculator">288 / 24</gadget>
<output>12</output>

<gadget id="calculator">27 * 12</gadget>
<output>324</output>

<gadget id="calculator">324 - 288</gadget>
<output>36</output>

<gadget id="calculator">27 - 18</gadget>
<output>9</output>

<gadget id="calculator">36 / 9</gadget>
<output>4</output>

<result>4</result>