Gretchen read that you should spend 10 minutes walking for every 90 minutes you spend sitting. If Gretchen spends 6 hours working at her desk, how long will she spend walking?
Let's be accurate as possible and think first.
40
First find the total number of minutes Gretchen spends sitting at her desk: 6 hours * 60 minutes / hour = 360 minutes.

Then divide this amount by 90 minutes to find how many walking breaks Gretchen takes: 360 minutes / 90 minutes / break = 4 breaks.

Then multiply the number of breaks by the length of each break to find how long Gretchen spends walking: 4 breaks * 10 minutes / break = 40 minutes.

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Therefore, the answer is 40