In order to create a "resource-conserving society", a certain district stipulates the charging standard for electricity consumption as follows: 0.4 yuan per month for the part of the electricity consumption of each household that does not exceed 10 kWh, and 0.9 yuan per kWh for the part that exceeds 10 kWh but not more than 20 kWh The charge is 1.7 yuan per degree for the part exceeding 20 degrees. In April this year, Uncle Zhang’s family paid 5.3 yuan more than Aunt Li’s electricity bill, and Aunt Li’s family paid 6.6 yuan more than Grandma Wang’s. So how much electricity bills did Uncle Zhang, Aunt Li and Grandma Wang pay in total in April?
为创建"资源节约型社会"，某区对用电的收费标准规定如下：每月每户用电不超过10度的部分按0.4元收费，超过10度而不超过20度部分按每度0.9元收费，超过20度的部分按每度1.7元收费．今年四月份，张叔叔家比李阿姨多交电费5.3元，李阿姨家比王奶奶家多交6.6元，那么张叔叔、李阿姨和王奶奶三家四月份共交电费多少元？
<gadget id="calculator">10 * 0.4</gadget>
<output>4</output>

<gadget id="calculator">10 * 0.9</gadget>
<output>9</output>

<gadget id="calculator">4 + 9 + 1.7</gadget>
<output>14.7</output>

<gadget id="calculator">6 * 0.9</gadget>
<output>5.4</output>

<gadget id="calculator">4 + 5.4</gadget>
<output>9.4</output>

<gadget id="calculator">10 - 6</gadget>
<output>4</output>

<gadget id="calculator">4 * 0.4</gadget>
<output>1.6</output>

<gadget id="calculator">14.7 + 9.4 + 1.6</gadget>
<output>25.7</output>

<result>25.7</result>