Xiaohua is 5 years old this year. When he was 12 years old, his mother was just 40 years old. How old is his mother?
小华今年5岁，他长到12岁时，妈妈正好40岁，妈妈今年多少岁？
<gadget id="calculator">12 - 5</gadget>
<output>7</output>

<gadget id="calculator">40 - 7</gadget>
<output>33</output>

<result>33</result>