How do you convert 7.8 km to miles?

##x = 4.875 " miles"##

You need to know a conversion factor.

5 miles = 8 km OR 1 mile = 8/5 km OR 1 km = 5/8 mile

For the same distance, the number of miles is less than the number of km.

##7.8 km xx 5/8 = 4.875 " miles"##

Or by direct proportion:

##("miles")/("km") = x/7.8 = 5/8##

##x = (7.8xx5)/8##

##x = 4.875 " miles"##