A city collects water charges according to the following regulations: if the water used by each household does not exceed 20 cubic meters per month, it will be charged at 2.2 yuan per cubic meter; if it exceeds 20 cubic meters, the excess will be charged at 3 yuan per cubic meter. If the average water price paid by a user this month is 2.5 yuan, how many cubic meters of water did the user use this month?
某市收取水费按以下规定：若每月每户用水不超过20立方米，则每立方米按2.2元收费，若超过20立方米，则超过的部分按每立方米3元收费．如果某用户这个月所交的平均水价是2.5元，那么该用户这个月用了多少立方米的水？
<gadget id="calculator">3 * 20</gadget>
<output>60</output>

<gadget id="calculator">2.2 * 20</gadget>
<output>44</output>

<gadget id="calculator">60 - 44</gadget>
<output>16</output>

<gadget id="calculator">3 - 2.5</gadget>
<output>0.5</output>

<gadget id="calculator">16 / 0.5</gadget>
<output>32</output>

<result>32</result>