A bag of rice, eat 40% of the whole on the first day, eat the remaining 50% on the second day, and eat the remaining 75% on the third day. At this time, there is still 15 kg left. Find the original weight of the rice?
大米一包，第一天吃了全部的40%，第二天吃了余下的50%，第三天吃了余下的75%，这时还剩下15公斤，求原来大米的重量？
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

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

<gadget id="calculator">(3/5) * (1/2)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 - (2/5) - (3/10)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">75 / 100</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(3/10) * (1/4)</gadget>
<output>3/40 = around 0.075</output>

<gadget id="calculator">15 / (3/40)</gadget>
<output>200</output>

<result>200</result>