The age difference between mother and daughter is 30 years old, and the age ratio between mother and daughter is 4:1, so how old is the daughter?
母女俩的年龄差是30岁，母女俩的年龄比是4：1，那么女儿是多少岁
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">30 / (3/4)</gadget>
<output>40</output>

<gadget id="calculator">40 * (1/4)</gadget>
<output>10</output>

<result>10</result>