Use metal strips to make the frame of the cuboid counter. A 20-meter-long metal strip is used to make this counter. The counter is 3 meters long and 0.8 meters wide. What is the height?
用金属条制作长方体柜台的框架，做这个柜台用了20米长的金属条，柜台长3米，宽0.8米，高是多少？
<gadget id="calculator">20 / 4</gadget>
<output>5</output>

<gadget id="calculator">3 + 0.8</gadget>
<output>3.8</output>

<gadget id="calculator">5 - 3.8</gadget>
<output>1.2</output>

<result>1.2</result>