In May of a certain year, cloudy days are less than sunny days (1/3), rainy days are less than sunny days (3/5), how many sunny days are there in this month?
某年的五月中，阴天比晴天少(1/3)，雨天比晴天少(3/5)，这个月晴天有多少天．
<gadget id="calculator">10 + 6 + 15</gadget>
<output>31</output>

<gadget id="calculator">31 / 31</gadget>
<output>1</output>

<gadget id="calculator">1 * 15</gadget>
<output>15</output>

<result>15</result>