A pile of coal weighs 10 tons. After 10% is used up, another 3 tons are brought in. How many tons is the pile of coal now?
一堆煤重10吨，用去10%后，又运进3吨，现在这堆煤有多少吨．
<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 - (1/10)</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">10 * (9/10)</gadget>
<output>9</output>

<gadget id="calculator">9 + 3</gadget>
<output>12</output>

<result>12</result>