Answer:
16 miles
Explanation:
If 1.5 inches is equal to 4 miles, it would also mean that 3 inches is equivalent to 8 miles, since 4*2=8 and 1.5*2=3. Since we need to find it for 6 inches, we just double the number again to get 6 inches = 16 miles. (3*2=6; 8*2=16)