After Guangming Central Primary School changed the old-fashioned faucet into a water-saving faucet, it saved 2 tons of water every week compared with before. How many tons of water is saved on average every day?
光明中心小学把老式水龙头改成节水型龙头后，每个星期比以前节约用水2吨，平均每天节约用水几分之几吨？
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<result>2/7 = around 0.285714</result>