A pile of sand and gravel, 35 tons have been used, and 15 tons are left. What percentage of the pile of sand and gravel is the remaining sand and gravel?
一堆沙石，用去35吨，还剩15吨，剩下的沙石占这堆沙石的几分之几？
<gadget id="calculator">35 + 15</gadget>
<output>50</output>

<gadget id="calculator">15 / 50</gadget>
<output>3/10 = around 0.3</output>

<result>3/10 = around 0.3</result>