In order to encourage citizens to save water, the water company stipulates that each household will be charged at 2.90 yuan per ton for water consumption within 10 tons (including 10 tons) per month; if it exceeds 10 tons, the excess tonnage will be charged at 8.00 yuan per ton. Xiaogang’s family paid a water fee of 73.00 yuan last month. Please help me figure out how many tons of water was used by Xiaogang’s family last month?
为鼓励市民节约用水，自来水公司规定：每户每月用水10吨以内(含10吨)，按每吨2.90元收费；超过10吨的，其超出吨数按每吨8.00元收费．小刚家上个月交水费73.00元，请你帮助算一算，小刚家上个月用水多少吨？
<gadget id="calculator">10 * 2.9</gadget>
<output>29</output>

<gadget id="calculator">73 - 29</gadget>
<output>44</output>

<gadget id="calculator">44 / 8</gadget>
<output>11/2 = around 5.5</output>

<gadget id="calculator">10 + (11/2)</gadget>
<output>31/2 = around 15.5</output>

<result>31/2 = around 15.5</result>