1/4 of the total money is used to buy a pen, and 8 yuan is spent to buy a storybook. At this time, the ratio of the money used to the remaining money is 7:5. Do you know how much money is left?
买钢笔用去总钱数的(1/4)，买故事书用去8元，这时用去的钱数与剩下的钱数比是7：5．你知道还剩下多少钱吗？
<gadget id="calculator">7 + 5</gadget>
<output>12</output>

<gadget id="calculator">7 / 12</gadget>
<output>7/12 = around 0.583333</output>

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

<gadget id="calculator">(7/12) - (1/4)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">8 / (1/3)</gadget>
<output>24</output>

<gadget id="calculator">5 / 12</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">24 * (5/12)</gadget>
<output>10</output>

<result>10</result>