I drove to the beach at a rate of 40 miles per hour. If I had driven at a rate of 42 miles per hour instead, then I would have arrived 45 minutes later. How many miles did I drive?
D/40 ==T, [T==Time]
D/42==T - 45/60, solve for D, T
Use substitution to get:
D==630 miles to the beach !!
I drove to the beach at a rate of 40 miles per hour. If I had driven at a rate of 42 miles per hour instead, then I would have arrived 45 minutes later. How many miles did I drive?
Are you sure you copied the problem correctly?
It doesn't make sense to drive faster and arrive later.
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