To build a road with a length of 40.5 kilometers, at the beginning, an average of 4.5 kilometers was repaired every day. After 4 days of repairing, the rest should be completed within 3 days. How many kilometers should be repaired at least every day?
修一条长40.5千米的路，开始时平均每天修4.5千米，修了4天，剩下的要在3天内完成，剩下的最少每天修多少千米？
<gadget id="calculator">4.5 * 4</gadget>
<output>18</output>

<gadget id="calculator">40.5 - 18</gadget>
<output>22.5</output>

<gadget id="calculator">22.5 / 3</gadget>
<output>7.5</output>

<result>7.5</result>