My mother is 46 years old this year, and Xiaohua is 16 years old this year. When my mother was 7 times Xiaohua's age.
妈妈今年46岁，小华今年16岁，当妈妈多少岁时，正好是小华年龄的7倍．
<gadget id="calculator">46 - 16</gadget>
<output>30</output>

<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">1 - (1/7)</gadget>
<output>6/7 = around 0.857143</output>

<gadget id="calculator">30 / (6/7)</gadget>
<output>35</output>

<result>35</result>