There are (5/6) tons of cement in a pile, (1/5) tons are used to repair the road, and 350 kilograms are used to build a house. How many tons of cement are left useless?
一堆水泥有(5/6)吨，修路面用去(1/5)吨，盖房子用去350千克，还剩多少吨水泥没有用？
<gadget id="calculator">5 / 6</gadget>
<output>5/6 = around 0.833333</output>

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

<gadget id="calculator">7 / 20</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">(5/6) - (1/5) - (7/20)</gadget>
<output>17/60 = around 0.283333</output>

<result>17/60 = around 0.283333</result>