A bag of rice, 25% of the whole food was eaten in the first week, and 20% of the whole food was eaten in the second week. A total of 9 kilograms were eaten. How many kilograms did this bag of rice originally weigh?
一袋米，第一周吃了全部的25%，第二周吃了全部的20%，一共吃了9千克，这袋米原来有多少千克？
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/4) + (1/5)</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">9 / (9/20)</gadget>
<output>20</output>

<result>20</result>