A steel pipe is used up (3/4), leaving 20 decimeters, how many decimeters does this steel pipe have?
一根钢管，用去(3/4)，剩下20分米，这根钢管原有多少分米？
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">20 / (1/4)</gadget>
<output>80</output>

<result>80</result>