If every inch is scaled up to 7 miles, you can find how many miles 6in is by multiplying by 7. 6x7=42 So the answer is 42 miles.
Another way to think about it is as 7mil + 7mil + 7mil + 7mil + 7mil + 7mil=42 miles (You add the 7 six times since it is 6in and each inch is 7miles)