Hongguang Primary School will start summer vacation on July 15th, and start school on September 1st. How many days will it be on vacation?
红光小学从7月15日开始放暑假，9月1日开学，放假多少天．
<gadget id="calculator">31 - 15</gadget>
<output>16</output>

<gadget id="calculator">16 + 1 + 31</gadget>
<output>48</output>

<result>48</result>