pile of sand, after part of it is used, there is still (1/4) ton left, which happens to be used (1/5). How many tons is this pile of sand?
一堆沙子，用去一部分后还剩(1/4)吨，正好是用去的(1/5)．这堆沙子共多少吨？
<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) / (1/5)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">(5/4) + (1/4)</gadget>
<output>3/2 = around 1.5</output>

<result>3/2 = around 1.5</result>