Answer:
868 miles
Explanation:
cm to miles ? are you sure you got the problem description right ? because cm are part of the metric system (mm, cm, meters, kilometers), while miles are part of American/ UK systems. and they don't deal with cm.
but ok, so, we will not deal with conversion rates, we will just apply the scale factors.
2.5 cm <-> 620 miles
3.5 cm <-> ? miles
that is determined by the factor to go from 2.5 to 3.5 cm. the same factor then had to be applied to the miles.
2.5 × f = 3.5
f = 3.5 / 2.5 = 7/2 / 5/2 = 7/2 × 2/5 = 7×2 / 2×5 = 7/5
=>
620 × 7/5 = 868 miles