50
Step-by-step explanation:
You set this up with a ratio, 1:20 or 1 equals 20 miles. So i'm multiplying by 20 regardless. Now I have 2 and a half inches or you can say 2.5. Multiply 2.5 (on paper..) and 20 and there you go. 20 times 2 equals 40 and 20 times a half is 10, 40 + 10= 50.
