Answer:
Hope it helps you :)
And i hope you understand
For store 1, it can be placed on 16 sites. Store 2 can be placed on 15 sites( since store 1 is already on site 1). Store 3 can be placed on 14 sites and so on until store 5 which has 12 sites.
Therefore the number of way is
C= 16*15*14*13*12
c=524,160 possibilities