The tap water charging standard for residents in a certain city is as follows: 1.80 yuan per ton for each household’s water consumption within 4 tons (including 4 tons) per month; when it exceeds 4 tons, 3.00 yuan per ton for the excess. In March, Xiaoming’s family paid a total of 11.7 yuan for water. How many tons of water does his family share this month?
某市居民自来水收费标准如于：每月每户用水4吨以内(包括4吨)，每吨1.80元；当超过4吨时，超过部分每吨3.00．三月份小明家共交水费11.7元，这个月他家共用水多少吨？
<gadget id="calculator">1.8 * 4</gadget>
<output>7.2</output>

<gadget id="calculator">11.7 - 7.2</gadget>
<output>4.5</output>

<gadget id="calculator">4.5 / 3</gadget>
<output>1.5</output>

<gadget id="calculator">1.5 + 4</gadget>
<output>5.5</output>

<result>5.5</result>