At the end of last year, the Qingfeng community switched to using water-saving faucets. Grandma Wang’s family saved 34.5 yuan in water bills in the first half of the year, and Grandma Li’s house saved 21 yuan in water bills in the second quarter. Which family saves the most water bills per month on average? How much more?
清风小区去年年底全部改用节水龙头，王奶奶家上半年节约水费34.5元，李奶奶家第二季度节约水费21元，谁家平均月节约的水费多？多多少元？
<gadget id="calculator">21 / 3</gadget>
<output>7</output>

<gadget id="calculator">34.5 / 6</gadget>
<output>5.75</output>

<gadget id="calculator">7 - 5.75</gadget>
<output>1.25</output>

<result>1.25</result>