There is a batch of goods in the warehouse. After being shipped out (2/5), 30 tons are brought in again. At this time, the goods in the warehouse are exactly the original (3/4). How many tons of goods were originally in the warehouse?
仓库里有一批货物，运出(2/5)后，又运进30吨，这时仓库里的货物正好是原来的(3/4)．仓库里原来有货物多少吨？
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">2 / 5</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">(3/4) - (3/5)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">30 / (3/20)</gadget>
<output>200</output>

<result>200</result>