Question

on a map 3 inches represents 240 miles. five inches represents 400 miles. how many inches would be needed to represent 320 miles

Answer 1

This was better.
\[3i=240m \implies i=80m\]
\[5i=400m \implies i=80m\]
\[x*i=320m\]

Answer 2

3inches=240miles
1inch=80miles
It's the same for the five inches rep 400miles

So ,
320miles= (1/80)x320=4

Another easier way of saying,
1mile=3/240
320miles=(3/240)x320=4

Answer 3

4 inches