The Feicheng Fertilizer Plant saved 8.4 tons of coal in the first 3 days of the week, and 14.7 tons of coal in the last 4 days. In this way, the actual coal consumption was 170 tons. How many tons of coal did the fertilizer plant save on average this week?
肥城化肥厂在一星期的前3天共节约用煤8.4吨，后4天节约用煤14.7吨，这样实际用煤170吨，化肥厂这一星期平均每天节约用煤多少吨？
<gadget id="calculator">8.4 + 14.7</gadget>
<output>23.1</output>

<gadget id="calculator">3 + 4</gadget>
<output>7</output>

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

<result>3.3</result>