For a batch of steel, (5/18) tons are used for the first time, (7/10) tons are used for the second time, and (3/5) of this batch of steel is left. How many tons are there in this batch of steel?
一批钢材，第一次用去(5/18)吨，第二次用去(7/10)吨，还剩下这批钢材的(3/5)，这批钢材有多少吨？
<gadget id="calculator">44 / 35</gadget>
<output>44/35 = around 1.257143</output>

<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">(44/35) * (5/2)</gadget>
<output>22/7 = around 3.142857</output>

<result>22/7 = around 3.142857</result>