In order to save energy, a city charges natural gas fees according to the following regulations: if the gas consumption is less than 50m**3, the charge is 2.1 yuan per m**3; if the gas consumption exceeds 50m**3, the excess part is charged 2.5 yuan per m**3. Xiaoming’s family paid 217.5 yuan in December, how much m**3 is Xiaoming’s household natural gas this month?
为了节省能源，某市按以下规定收取天然气费用：用气量不足50m**3，每m**3收费2.1元；如果超过50m**3，超过部分每m**3收费2.5元．小明家12月份缴费217.5元，这个月小明家用天然气多少m**3？
<gadget id="calculator">50 * 2.1</gadget>
<output>105</output>

<gadget id="calculator">217.5 - 105</gadget>
<output>112.5</output>

<gadget id="calculator">112.5 / 2.5</gadget>
<output>45</output>

<gadget id="calculator">45 + 50</gadget>
<output>95</output>

<result>95</result>