There are two old tortoises. Ten years ago, an expert said: "The sum of the ages of these two old tortoises is 400 years old, and the difference in age is 40 years old." According to the expert, the oldest tortoise this year How old are you?
有两只老龟，十年前一位专家说："这两只老龟年龄之和是400岁，年龄之差是40岁．"，按这位专家的说法，今年那只最老的龟是多少岁．
<gadget id="calculator">400 + 40</gadget>
<output>440</output>

<gadget id="calculator">440 / 2</gadget>
<output>220</output>

<gadget id="calculator">220 + 10</gadget>
<output>230</output>

<result>230</result>