There is a batch of rice in the cafeteria, 40% of it is used, and another 300 kg is bought. At this time, the amount of rice in the cafeteria is equivalent to (2/3) of the original amount. Ask how many kilograms of rice are there in the cafeteria?
食堂有一批大米，用去40%，又买进300千克，这时食堂大米的数量相当于原来数量的(2/3)．求食堂原来有多少千克大米？
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</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">(2/3) - (3/5)</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">300 / (1/15)</gadget>
<output>4_500</output>

<result>4_500</result>