A truck can transport ore 15 times a day on sunny days, but only 10 times a day on rainy days. It has been shipped for two weeks, a total of 190 times. How many of these days does it rain?
一辆卡车运送矿石，晴天每天可运15次，雨天每天只能运10次．它一连运了两个星期，共运了190次．这些天中有几天下雨？
<gadget id="calculator">210 - 190</gadget>
<output>20</output>

<gadget id="calculator">15 - 10</gadget>
<output>5</output>

<gadget id="calculator">20 / 5</gadget>
<output>4</output>

<result>4</result>