Math algebra
posted by Rose on .
the scale on aroad map indicates that 1/4 inch equals 20 miles. How far apart in miles are two towns that are 3 1/2 inches away on the map.

How many fourths are in 3 1/2? Ans:14
So the distance must be 14*20 
The answer in my book is 280. I can not figure out how to write the equation using proportiions using cross multiply. I have tried several ways and unable to get the answer in the book.

0.25 / 20 = 3.5 / x
Cross multiply:
0.25x = 70
x = 280 
Thank you !

3.5" x (20 miles/0.25") = ??
Check my work.