Sunshine Chemical Fertilizer Factory carried out water-saving activities. It saved 2.1 tons of water per day in the first 4 days of a certain week, and saved 14.7 tons of water in the last 3 days. How many tons of water was saved on average this week?
阳光化肥厂开展节水活动，某星期前4天每天节约用水2.1吨，后3天共节约用水14.7吨，这一星期平均每天节约用水多少吨？
<gadget id="calculator">2.1 * 4</gadget>
<output>8.4</output>

<gadget id="calculator">8.4 + 14.7</gadget>
<output>23.1</output>

<gadget id="calculator">23.1 / 7</gadget>
<output>3.3</output>

<result>3.3</result>