That entirely depends on the scale of the map in question.
Chat with our AI personalities
18cm * 5km/3cm = 6*5 km = 30 km
1 cm = 10-5 km (or 0.00001 km) So 8.13 cm = 8.13*10-5 km
Well, honey, if 3 cm on the map represents 18 km in real life, then you just need to do a little math. If Riverside and Smithville are 54 km apart in reality, on the map they would be 9 cm apart. So, grab a ruler and start measuring, darling!
If you are talking about metric measurements, 1 cm does not equal 5 km. There are 100,000 cms in a km, so 5 km is actually 500,000 cm To answer your question going along with your assumption that if 1cm = 5 km, there would be 8.5 km in 1.7cm (1.7 x 5 = 8.5)
1 cm = 10-2 metres =10-5 km So, 8.5 cm = 8.5*10-5 km = 0.000085 km