Uncle Zhang received (5/4) tons of watermelons, sold (1/5) tons on the first day, and sold (3/10) tons on the second day, how many tons are left?
张大伯收了(5/4)吨西瓜，第一天卖出(1/5)吨，第二天卖出(3/10)吨，还剩多少吨？
<gadget id="calculator">5 / 4</gadget>
<output>5/4 = around 1.25</output>

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

<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(5/4) - (1/5) - (3/10)</gadget>
<output>3/4 = around 0.75</output>

<result>3/4 = around 0.75</result>