There is a batch of books in a bookstore, sold on the first day (2/9), sold the rest (3/7) on the second day, and bought another batch of books on the third day, the quantity is the remaining after the second day’s sales In the lower half, there are 298 books of this kind in the bookstore at this time, and how many books of this kind originally existed in the bookstore.
某书店有一批图书，第一天售出(2/9)，第二天售出剩下的(3/7)，第三天又进了一批书，数量是第二天售出后剩下的一半，这时书店存有这类图书298本，书店原有这类图书多少本．
<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">1 - (2/9)</gadget>
<output>7/9 = around 0.777778</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">(7/9) * (3/7)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 - (2/9) - (1/3)</gadget>
<output>4/9 = around 0.444444</output>

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

<gadget id="calculator">(4/9) * (1/2)</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">(4/9) + (2/9)</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">298 / (2/3)</gadget>
<output>447</output>

<result>447</result>