Use a bucket of plasticine to make a four-wheeled car model. If all of them are used to make the body, you can make 20; if you use all of them to make wheels, you can make 120. How many car models can this barrel of plasticine make?
用一桶橡皮泥做一种四轮的汽车模型，如果全部做车身，可以做20个；如果全部用来做轮子，可以做120个．这桶橡皮泥可以做这样的整车模型多少辆？
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">4 / 120</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/20) + (1/30)</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">1 / (1/12)</gadget>
<output>12</output>

<result>12</result>