It takes 12 meters of plastic rope to make 3 ropes of the same length. According to this calculation, how many meters of plastic rope are needed to make 9 skipping ropes like this?
做3根同样长的绳子用去塑料绳12米，照这样计算，做这样的9根跳绳要塑料绳多少米？
<gadget id="calculator">12 / 3</gadget>
<output>4</output>

<gadget id="calculator">4 * 9</gadget>
<output>36</output>

<result>36</result>