The store originally sold (7/8) tons of salt, and sold (2/8) tons, how many tons are left?
商店原有盐(7/8)吨，卖出(2/8)吨，还剩下多少吨？
<gadget id="calculator">7 / 8</gadget>
<output>7/8 = around 0.875</output>

<gadget id="calculator">2 / 8</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(7/8) - (1/4)</gadget>
<output>5/8 = around 0.625</output>

<result>5/8 = around 0.625</result>