The mother squirrel picks pine cones. She can pick 20 pine cones a day in sunny days, but only 10 in rainy days. Once she picked 180 pine cones for several consecutive days, with an average of 18 pine cones a day. How many days are there sunny days?
松鼠妈妈采松果，晴天每天可采20棵，雨天每天只能采10颗，一次它连续几天共采了180棵松果，平均每天采18颗，这几天有多少天是晴天？
<gadget id="calculator">180 / 18</gadget>
<output>10</output>

<gadget id="calculator">10 * 20</gadget>
<output>200</output>

<gadget id="calculator">200 - 180</gadget>
<output>20</output>

<gadget id="calculator">20 - 10</gadget>
<output>10</output>

<gadget id="calculator">20 / 10</gadget>
<output>2</output>

<gadget id="calculator">10 - 2</gadget>
<output>8</output>

<result>8</result>