The wall is 624 feet long and made of 6,500 bamboo poles. How many
bamboo poles are there per foot, rounded to
the nearest whole number?

For this question you would simply divide the number of bamboo poles by the number of feet which would be:
6,500/624= 10.41666666666667
Since it says to round to the nearest whole number,

Your answer would be about 10 bamboo poles per feet