(3/4) tons of sand are shipped to the construction site, and (1/5) tons are shipped after (2/5) tons are used. How many tons of sand are there now?
建筑工地运来(3/4)吨沙子，用去(2/5)吨后又运来(1/5)吨，现在有多少吨沙子？
<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">(3/4) - (2/5)</gadget>
<output>7/20 = around 0.35</output>

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

<gadget id="calculator">(7/20) + (1/5)</gadget>
<output>11/20 = around 0.55</output>

<result>11/20 = around 0.55</result>