Wang Hong's family used 31 tons of water in the first quarter. After installing the water saving valve, they used 25 tons of water in the second quarter, saving 11.4 yuan in water costs compared with the first quarter. How much is the water fee per ton of water?
王宏家第一季度用水31吨，安上节水阀以后，第二季度用水25吨，比第一季度节约水费11.4元．每吨水的水费是多少元？
<gadget id="calculator">31 - 25</gadget>
<output>6</output>

<gadget id="calculator">11.4 / 6</gadget>
<output>1.9</output>

<result>1.9</result>