Mix cement, yellow sand, and stones at a ratio of 2:3:5 to make concrete. What percentage of the stones account for the concrete? How many
把水泥、黄沙、石子按2：3：5配制成混凝土，石子占混凝土的几分之几？多少
<gadget id="calculator">2 + 3 + 5</gadget>
<output>10</output>

<gadget id="calculator">5 / 10</gadget>
<output>1/2 = around 0.5</output>

<result>1/2 = around 0.5</result>