There are 50 tons of sand (1/5) is taken out first, and then (1/5) is added, how many tons of sand are there at this time?
有50吨沙子先取出它的(1/5)后，再增加它的(1/5)，这时沙子有多少吨？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 + (1/5)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">50 * (4/5) * (6/5)</gadget>
<output>48</output>

<result>48</result>