Pack a batch of apples into boxes. If 50 boxes are packed, 60% of the batch of apples will remain; if 80 boxes are packed, 900 apples will remain. How many apples are there in total?
将一批苹果装箱，如果装50箱，还剩这批苹果的60%；如果装80箱，还剩900个．这批苹果一共有多少个．
<gadget id="calculator">60 / 100</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 - (3/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">50 / (2/5)</gadget>
<output>125</output>

<gadget id="calculator">125 - 80</gadget>
<output>45</output>

<gadget id="calculator">900 / 45</gadget>
<output>20</output>

<gadget id="calculator">20 * 125</gadget>
<output>2_500</output>

<result>2_500</result>