Mingming is 12 years old this year, and Yuanyuan is 10 years old. How long ago, the age of Mingming and Yuanyuan is 18 years old.
明明今年12岁，园园10岁，多少时候，明明和园园的年龄和为18岁．
<gadget id="calculator">22 - 18</gadget>
<output>4</output>

<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<result>2</result>