The water used in October is 85% of that in September. How much water is saved in October compared to September?
十月份用水是九月份的85%，十月份比九月份节约用水多少．
<gadget id="calculator">85 / 100</gadget>
<output>17/20 = around 0.85</output>

<gadget id="calculator">1 - (17/20)</gadget>
<output>3/20 = around 0.15</output>

<result>3/20 = around 0.15</result>