Xinghua Supermarket shipped a batch of watermelons and sold (3/7) tons on the first day, which was (1/9) more tons than the second day. How many tons were sold in total in two days.
兴华超市运来一批西瓜，第一天卖出(3/7)吨，比第二天多(1/9)吨．两天一共卖出多少吨．
<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">1 / 9</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">(3/7) - (1/9)</gadget>
<output>20/63 = around 0.31746</output>

<gadget id="calculator">(20/63) + (3/7)</gadget>
<output>47/63 = around 0.746032</output>

<result>47/63 = around 0.746032</result>