Respuesta :

so 450 miles per hour
to see how many miles in 18 minutes you must see how many in a minute

an hour has 60 minutes
so divide 450 by 60 to see how many miles per minute 
that is 15/2 miles per minute
now to see how many miles in 18 minutes
multiply 15/2 * 18 
that is 135 miles in 18 minutes

Hope this helps :)