The older brother is 21 years old this year, and the younger brother is 15 years old this year. When the combined age of the elder brother and younger brother reaches 100 years old, how old is the elder brother? How many
今年哥哥21岁，弟弟今年15岁，当哥弟年龄之和达100岁时，哥哥是多少岁？多少
<gadget id="calculator">100 - 21 - 15</gadget>
<output>64</output>

<gadget id="calculator">1 + 1</gadget>
<output>2</output>

<gadget id="calculator">64 / 2</gadget>
<output>32</output>

<gadget id="calculator">21 + 32</gadget>
<output>53</output>

<result>53</result>