Plan to burn 90 tons of coal, but the actual amount of coal burned is (1/10) less than the plan, how much is the actual amount of coal burned?
计划烧煤90t，实际烧煤比计划节约了(1/10)，实际烧煤多少t．
<gadget id="calculator">1 / 10</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">90 * (9/10)</gadget>
<output>81</output>

<result>81</result>