Uncle Wang sells 7 kilograms of watermelon for 20 yuan. If he sells 21 kilograms of watermelon, how much will he get?
王叔叔卖7千克西瓜得20元，如果他卖21千克西瓜得多少元．
<gadget id="calculator">20 / 7</gadget>
<output>20/7 = around 2.857143</output>

<gadget id="calculator">(20/7) * 21</gadget>
<output>60</output>

<result>60</result>