The scale of a map is 7ft = 14.4 mi map: ft actual: 24.6 mi

The answer to the question can be found by setting up a proportion such as 7/14.4=x/24.6 which gives you 11.9583 ft

You can create a proportion

map:ft       7             x

actual:m   14.4       24.6

then cross multiply 14.4x/172.2
then divide 172.2 divided by 14.4 
11.958333333333