A film is 7,000 centimeters long, and one-third of its length is screened in 15 minutes. If so, how many minutes will it take to finish the screening? (Solve in five ways, one of which must be a proportional solution)
一部影片长7000厘米，15分钟放映了全长的三分之一，照这样，剩下还要几分钟才能放映完？(用五种方法解答，其中要有一种比例解)
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 / 45</gadget>
<output>1/45 = around 0.022222</output>

<gadget id="calculator">(2/3) / (1/45)</gadget>
<output>30</output>

<result>30</result>