A bottle of shampoo has been used up (1/4), and there is still (9/10) liters left. How many liters is in this bottle of shampoo?
一瓶洗发水用去了(1/4)，还剩下(9/10)升，这瓶洗发水有多少升？
<gadget id="calculator">9 / 10</gadget>
<output>9/10 = around 0.9</output>

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

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">(9/10) / (3/4)</gadget>
<output>6/5 = around 1.2</output>

<result>6/5 = around 1.2</result>