Changsheng Farm needs to harvest 16.4 hectares of wheat, and it has been harvesting for 3 days, harvesting 1.8 hectares every day. If 2.2 hectares are harvested every day from the fourth day, how many days will it take for the remaining wheat to be harvested?
昌盛农场要收割小麦16.4公顷，已经收割了3天，每天收割1.8公顷．如果从第四天起，每天收割2.2公顷，那么，剩下的小麦还需多少天收割完？
<gadget id="calculator">1.8 * 3</gadget>
<output>5.4</output>

<gadget id="calculator">16.4 - 5.4</gadget>
<output>11</output>

<gadget id="calculator">11 / 2.2</gadget>
<output>5</output>

<result>5</result>