Xiaoming's family now uses 12 tons of water per month, which is 3 tons less than before. How much is the savings?
小明家现在每月用水12吨，比原来每月节约3吨，节约了百分之几？
<gadget id="calculator">12 + 3</gadget>
<output>15</output>

<gadget id="calculator">3 / 15</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>