A box is filled with solid balls, and the box weighs 12 kg. After removing (1/4) of the solid ball from the box, the remaining solid balls together with the box weigh 9.5 kg. How many kilograms does the box weigh.
一个箱子里装满了实心球，连箱子共重12千克．从箱中取出实心球的(1/4)后，剩下的实心球连箱共重9.5千克．箱子重多少千克．
<gadget id="calculator">12 - 9.5</gadget>
<output>2.5</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">2.5 / (1/4)</gadget>
<output>10</output>

<gadget id="calculator">12 - 10</gadget>
<output>2</output>

<result>2</result>