In order to make better use of water resources, a certain city has formulated a residential water charge standard. If a household’s monthly water consumption does not exceed 15 cubic meters (including 15 cubic meters), it will be charged at 1.8 yuan per cubic meter. If it exceeds 15 cubic meters, The excess part is charged at 2.3 yuan per cubic meter. In addition, an additional sewage treatment fee of 1 yuan is charged per cubic meter. If a household pays a total of 58.5 yuan for water in January. What is the cubic meter of water consumption of this household in January?
某市为了更好的利用水资源，制定了居民用水收费标准，如果一户每月用水量不超过15立方米(含15立方米)，每立方米按1.8元收费，如果超过15立方米，超过部分按每立方米2.3元收费．另外，每立方米加收污水处理费1元，如果某户一月份共支付水费58.5元．求该户一月份用水量是多少立方米？
<gadget id="calculator">1.8 + 1</gadget>
<output>2.8</output>

<gadget id="calculator">2.8 * 15</gadget>
<output>42</output>

<gadget id="calculator">58.5 - 42</gadget>
<output>16.5</output>

<gadget id="calculator">2.3 + 1</gadget>
<output>3.3</output>

<gadget id="calculator">16.5 / 3.3</gadget>
<output>5</output>

<gadget id="calculator">15 + 5</gadget>
<output>20</output>

<result>20</result>