A container is exactly filled with 10 liters of pure alcohol. After pouring out 3 liters, it is filled with water. After pouring out another 3.5 liters, it is then filled with water. What is the concentration of the solution in the container at this time?
一容器正好装满10升纯酒精，倒出3升后用水加满，再倒出3.5升后，再用水加满，这时容器中溶液的浓度是多少？
<gadget id="calculator">10 - 3</gadget>
<output>7</output>

<gadget id="calculator">7 / 10</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">3.5 * (7/10)</gadget>
<output>2.45</output>

<gadget id="calculator">10 - 3 - 2.45</gadget>
<output>4.55</output>

<gadget id="calculator">4.55 / 10</gadget>
<output>0.455</output>

<result>0.455</result>