Amap has a scale of 5 cm : 18 km. if newton rsm is 12 km away from the riverside train station, how far apart are they on the map?

You're going to have to set up a proportion. So it'd be 5:18=x:12 or if in fraction form, 5/18=x/12. Then you cross multiply. Where you get 5*12=18x. Then isolate the variable, (60/18) and you get 3.33 cm. 

Bi’m pretty sure hope it works