A food factory uses a batch of flour to produce cakes. After 5 days of production, the ratio of the remaining flour to the used flour is 1:8. At this time, add another 2 tons of flour, just enough for one day's production. How many tons does this batch of flour have?
某食品厂用一批面粉生产糕点，生产5天后，剩下的面粉与用去面粉的比是1：8．这时再增加2吨面粉，才能正好够一天的生产用量，原来这批面粉共有多少吨．
<gadget id="calculator">8 / 9</gadget>
<output>8/9 = around 0.888889</output>

<gadget id="calculator">(8/9) / 5</gadget>
<output>8/45 = around 0.177778</output>

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

<gadget id="calculator">(8/45) - (1/9)</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">2 / (1/15)</gadget>
<output>30</output>

<result>30</result>