Lingling is 11 years old, and her grandfather is 74 years old. After many years, grandpa's age will be four times that of Lingling's.
玲玲今年11岁，爷爷今年74岁．再过多少年，爷爷的年龄是玲玲年龄的4倍．
<gadget id="calculator">74 - 11</gadget>
<output>63</output>

<gadget id="calculator">4 - 1</gadget>
<output>3</output>

<gadget id="calculator">63 / 3</gadget>
<output>21</output>

<gadget id="calculator">21 - 11</gadget>
<output>10</output>

<result>10</result>