Construction workers bring in 10 tons of cement, gravel, and sand each, and mix them into concrete at a ratio of 5:2:3. If the cement is just used up, how many tons of sand are left?
建筑工人运来水泥、石子、沙子各10吨，按5：2：3的比例配成混凝土，如果水泥正好用完，沙子还剩多少吨？
<gadget id="calculator">5 + 2 + 3</gadget>
<output>10</output>

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

<gadget id="calculator">10 / (1/2)</gadget>
<output>20</output>

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

<gadget id="calculator">20 * (3/10)</gadget>
<output>6</output>

<gadget id="calculator">10 - 6</gadget>
<output>4</output>

<result>4</result>