Problem: Lexington, and Elizabethtown, Kentucky are 79 miles apart. If the distance on the map is 2 1/2 inches, find the scale of the map.

Question

do i make a ratio for inches to miles?
is it 2.5x inches = 79 miles?

Answer 1

yes, but usually a unit of 1 is used

2.5 inches : 79 miles
1 inch : 79/2.5 mile
1 inch : 31.6 miles

If you use the same units, they can be skipped in the scale ...
31.6 miles = (31.6)(12)(5280) inches
2002176 inches

so you could state the scale as

1 : 2,002,176

Answer 2

Thanks!