There are 3 tons of rice in the store, and 4200 kilograms are shipped in. It is planned to sell them out in 9 days. How many kilograms will be sold on average every day?
商店有3吨大米，又运来4200千克，计划9天卖完，平均每天要卖多少千克？
<gadget id="calculator">3 * 1_000</gadget>
<output>3_000</output>

<gadget id="calculator">3_000 + 4_200</gadget>
<output>7_200</output>

<gadget id="calculator">7_200 / 9</gadget>
<output>800</output>

<result>800</result>