A bag of rice, 40% of it was eaten in the first week, 13 kg in the second week, and 5 kg was left. How many kg of rice was in this bag?
一袋大米，第一周吃了40%，第二周吃了13千克，还剩5千克，这袋大米原有多少千克？
<gadget id="calculator">13 + 5</gadget>
<output>18</output>

<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">18 / (3/5)</gadget>
<output>30</output>

<result>30</result>