There are two kinds of figures △ and □, △ accounts for (1/6) of the total, and then put 3 △, △ accounts for (1/3) of the total, how many original △.
有△、□两种图形，△占总数的(1/6)，再放入3个△，△就占总数的(1/3)，原有△多少个．
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">3 * (1/3)</gadget>
<output>1</output>

<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(1/3) - (1/6)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">2 / (1/6)</gadget>
<output>12</output>

<gadget id="calculator">12 * (1/6)</gadget>
<output>2</output>

<result>2</result>