A bottle of oil weighs (8/9) kg, and (1/4) kg is used up. How many kilograms of oil are left?
一瓶油重(8/9)kg，用去了(1/4)kg．还剩油多少千克？
<gadget id="calculator">8 / 9</gadget>
<output>8/9 = around 0.888889</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(8/9) - (1/4)</gadget>
<output>23/36 = around 0.638889</output>

<result>23/36 = around 0.638889</result>