Answer :
[tex]1km=1,000m\\1m=100cm\\therefore\\1km=1,000\cdot100cm=100,000cm\\----------------------\\\\15km=15\cdot100,000cm=1,500,000cm\\\\\boxed{1cm:15km\Rightarrow 1cm:1,500,000cm\Rightarrow1:1,500,000}\leftarrow scale\ of\ a\ map\\\\1cm\ of\ the\ map\ is\ equal\ 1,500,000cm\ of\ real\ distance\\1cm\ of\ the\ map\ is\ equal\ 15km\ of\ real\ distance[/tex]
for every one cm on the map that you measure, you count that as 15 km so if there is a mark 2.5 cm then you count that as 37.5km in real life
