Warehouse A stores 280 tons of grain. If 30% of the grain stored in Warehouse B is transported away, the remaining quantity is equal to the quantity of grain stored in Warehouse A. How many tons of grain will be transported from Warehouse B?
甲仓库存粮280吨，如果把乙仓库存粮的30%运走后，剩下的数量与甲仓库的存粮数量相等，乙仓库运走存粮多少吨？
<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 - (3/10)</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">280 / (7/10)</gadget>
<output>400</output>

<result>400</result>