A basket of watermelons weighs 60kg in total. After selling (3/4) of the watermelons, the weight of the basket is 18kg. What is the weight of the basket? ．
一筐西瓜连筐共重60kg，卖了(3/4)的西瓜后连筐重18kg，筐重多少kg．．
<gadget id="calculator">60 - 18</gadget>
<output>42</output>

<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">42 / (3/4)</gadget>
<output>56</output>

<gadget id="calculator">60 - 56</gadget>
<output>4</output>

<result>4</result>