This year, Uncle Wang’s age is equivalent to Teacher Zhang’s (4/7), and 12 years later, Uncle Wang’s age is exactly equivalent to Teacher Zhang’s (2/3). How old is Teacher Zhang this year?
今年王叔的年龄相当于张老师的(4/7)，12年后，王叔的年龄又正好相当于张老师的(2/3)，今年张教师多少岁？
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">(2/3) * 12</gadget>
<output>8</output>

<gadget id="calculator">12 - 8</gadget>
<output>4</output>

<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">(2/3) - (4/7)</gadget>
<output>2/21 = around 0.095238</output>

<gadget id="calculator">4 / (2/21)</gadget>
<output>42</output>

<result>42</result>