Answer:
To calculate the percentage difference between the highest and lowest price cities for the cost of retail space, we need to use the following formula:
% difference = (|highest value - lowest value| / average value) x 100%
where "|" denotes absolute value.
Let's say the cost of retail space in the highest price city is $200 per square foot, and the cost in the lowest price city is $100 per square foot. If the average cost of retail space across all cities is $150 per square foot, then we can plug in the values to get:
% difference = (|$200 - $100| / $150) x 100% = (|$100| / $150) x 100% = 66.67%
Therefore, the highest price city is 66.67% more expensive than the lowest price city for the cost of retail space. Rounding this value to the nearest whole percentage gives us a percentage difference of 67%.