Someone asked Xiaohu how old he was this year. He made up an interesting math problem and replied: "Grandpa, Dad and I, the sum of the ages of the three is 120 years old, and Grandpa is 30 years older than Dad. 100 years older, how old do you think Xiaohu is this year?
有人问小虎今年几岁，他编了道有趣的数学题回答说："爷爷、爸爸和我，三个人年龄的和是120岁，爷爷比爸爸大30岁，爷爷和爸爸年龄之和正好比我大100岁，你猜小虎今年有多少岁？
<gadget id="calculator">120 - 100</gadget>
<output>20</output>

<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<result>10</result>