Two batches of steel were shipped to the campus expansion site of Xiamen Experimental Primary School, and the second batch was less than the first batch (1/5). After 15 tons of the second batch of steel are used, if (1/4) is taken out from the first batch and given to the second batch, the weight of the two batches of steel is just equal. How many tons was the first batch of steel delivered?
厦门实验小学校园扩建工地运来了两批钢材，第二批钢材比第一批少(1/5)．第二批钢材用去15吨后，如果从第一批中取出(1/4)给第二批，这时两批钢材的重量正好相等．运来的第一批钢材原来有多少吨？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

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

<gadget id="calculator">(1/4) - 1 - (1/5)</gadget>
<output>-19/20 = around -0.95</output>

<gadget id="calculator">(1/4) + 1 + (-19/20)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">15 / (3/10)</gadget>
<output>50</output>

<result>50</result>