The summer vacation starts on July 10th and starts on August 28th. How many days are there in total?
暑假从7月10日开始，8月28日开学，暑假共多少天．
<gadget id="calculator">31 - 10</gadget>
<output>21</output>

<gadget id="calculator">21 + 1 + 27</gadget>
<output>49</output>

<result>49</result>