2 cm= 100 mi
To find out how far town B is from A, you have to think about how if 2 cm=100 mi, then 3.5 cm=? You can now figure out that 3.5 cm= 175 mi.
Now all you have to do, is figure out how many miles 2cm is, and you get 100, because that is what the key says. Then you just add 100 to 175 to get 275 mi.
Hope this Helps!
Brainliest would be appreciated :P