Melissa drove at an average speed of 45 mi/h from her home in Memphis to visit her sister in Atlanta. She stayed in Atlanta 10 hours, and on the trip back averaged 60 mi/h. She returned home 43 hours after leaving. How many miles is Memphis from Atlanta?
) Write an equation using the information as it is given above that can be solved to answer this question. Use t as your varible to represent the amount of time Melissa spent driving from Memphis to Atlanta.
We know from the first part that the distance is equal to the speed multiplied by the time
d = st, or d = (45 mi/hr)t
we also know from the last part this same distance is
d = (60 mi/hr)(43 mi - 10 mi - t), or (60 mi/hr)(33 hr - t).
Now elliminate the d
(45 mi/hr)t = (60 mi/hr)(33 hr - t)
and solve for t.
Note: In professional work it is always a good idea to keep track of the units this way (they operate mathematically the same way as variables). But for this math problem it may be best to drop them. Do what's best for you though.
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