A school used 800 tons of water last year. This year it saves 15% of water compared with last year. How many tons of water is used this year?
某学校去年用水800吨，今年比去年节约用水一成五，今年用水多少吨？
<gadget id="calculator">15 / 100</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">1 - (3/20)</gadget>
<output>17/20 = around 0.85</output>

<gadget id="calculator">800 * (17/20)</gadget>
<output>680</output>

<result>680</result>