Xiaoqiang goes to buy cloth. If he buys 2 meters, there is still 8.9 yuan left. If he buys 4 meters of the same cloth, there is still a difference of 23.1 yuan. How much did you bring?
小强去买布，如果买2米还剩8.9元，如果买4米同样的布，还差23.1元．带了多少元．
<gadget id="calculator">23.1 + 8.9</gadget>
<output>32</output>

<gadget id="calculator">4 - 2</gadget>
<output>2</output>

<gadget id="calculator">32 / 2</gadget>
<output>16</output>

<gadget id="calculator">2 * 16</gadget>
<output>32</output>

<gadget id="calculator">32 + 8.9</gadget>
<output>40.9</output>

<result>40.9</result>