After a pile of sand is used (3/5), another 60 tons is transported in. The ratio of the weight of the sand at this time to the original is 1:2. How many tons is the original sand?
一堆沙，用去(3/5)后，又运进60吨，这时的沙重量与原来的比是1：2，原有沙多少吨？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 - (3/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(1/2) - (2/5)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">60 / (1/10)</gadget>
<output>600</output>

<result>600</result>