There are two films, the first one is shown for 25 minutes, the second one is shown for 21 minutes, and the film (film) is 30 meters long every minute. Which film is longer? How many meters long?
有两部电影，第一部放映用了25分钟，第二部放映了21分钟，每分钟放映影片(胶片)长30米，哪部影片长？长多少米？
<gadget id="calculator">30 * 25</gadget>
<output>750</output>

<gadget id="calculator">30 * 21</gadget>
<output>630</output>

<gadget id="calculator">750 - 630</gadget>
<output>120</output>

<result>120</result>