basket of fresh fish weighs 120 kilograms in total. Half of the fresh fish is sold first, and then the remaining half is sold. The remaining fish in the basket weighs 39 kilograms in total. How many kilograms of fish are there in the original basket?
一筐鲜鱼，连筐共重120千克，先卖出鲜鱼的一半，再卖出剩下的一半，剩下的鱼连筐共重39千克．原来筐里有鱼多少千克？
<gadget id="calculator">120 - 39</gadget>
<output>81</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/2)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) * (1/2)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/2) + (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">81 / (3/4)</gadget>
<output>108</output>

<result>108</result>