The mother is 40 years old this year, the son's age is the mother's (3/10), and it happens to be the grandmother's age (1/6). How old is grandma?
妈妈今年40岁，儿子的年龄是妈妈的(3/10)，又正好是外婆年龄的(1/6)．外婆今年多少岁？
<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">40 * (3/10)</gadget>
<output>12</output>

<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">12 / (1/6)</gadget>
<output>72</output>

<result>72</result>