answer:I’d say take the streets for a week. Each day record the time it takes you to take the streets. Find the average. From there, figure out how far you’re actually going on the streets and how far you’re going on the highway. (use google maps…or a long tape measure) ——————————————————————————- Time highway = Distance highway /Speed highway Take the streets when : Time streets < Time highway So: Time streets <Distance highway / Speed highway which yields Take the streets when: Speed highway < Distance highway / Time streets once you find the distance and time it should give you something like ” speed < 50 mph” Once you know that equation, there’s your rule.