A road construction team repaired a road, and built a total of 72 kilometers in the first 4 days, and a total of 180 kilometers in the next 5 days. How many kilometers are repaired per day on average?
某修路队修一条公路，前4天共修了72千米，后5天共修了180千米．平均每天修了多少千米？
<gadget id="calculator">72 + 180</gadget>
<output>252</output>

<gadget id="calculator">4 + 5</gadget>
<output>9</output>

<gadget id="calculator">252 / 9</gadget>
<output>28</output>

<result>28</result>