Answer:
To find the distance between Denny Way and Harrison St on Aurora Ave, you can subtract the distance between Mercer St and Denny Way from the distance between Mercer St and Harrison St on Broad St.
\[0.7 \text{ miles (Mercer St to Denny Way on Broad St)} - 0.4 \text{ miles (Denny Way to Harrison St on Broad St)} = 0.3 \text{ miles on Aurora Ave.}\]
Therefore, the distance between Denny Way and Harrison St on Aurora Ave is 0.3 miles.