Pack 3 kg of sugar into 10 bags on average, each bag is 3 kg ((())/(())), each bag is ((())/(())) kg; 7 bags are 3 kg ((())/(())), how many kilograms is 7 bags.
把3千克糖平均装成10袋，每袋是3千克的((())/(()))，每袋是((())/(()))千克；7袋是3千克的((())/(()))，7袋多少千克．
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / (1/10) / 1</gadget>
<output>10</output>

<gadget id="calculator">21 / 10</gadget>
<output>21/10 = around 2.1</output>

<result>21/10 = around 2.1</result>