The little rabbit can pick 30 mushrooms per day on a sunny day, but only 15 on a rainy day. It picked 360 pine nuts for several days, an average of 18 per day. So, how many of these days has it rained?
小兔子采蘑菇，晴天每天可以采30个，有雨的天每天只能采15个．它一连几天采了360个松籽，平均每天采18个．那么，这几天中有几天有雨？
<gadget id="calculator">360 / 18</gadget>
<output>20</output>

<gadget id="calculator">20 * 30</gadget>
<output>600</output>

<gadget id="calculator">600 - 360</gadget>
<output>240</output>

<gadget id="calculator">30 - 15</gadget>
<output>15</output>

<gadget id="calculator">240 / 15</gadget>
<output>16</output>

<result>16</result>