Here are the answer and explanation to yesterday’s practice question. Thanks for sending in all of your answers!

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Where are the 1′s coming from in this solution?

In addition, how does 1/A –> (A-1)/A? Is A being used as distance or work?

(A – 1)/A = A/A – 1/A = 1 – 1/A. After one minute 1/A has been pumped out. The 1 stands for the total job. So in 1 minute 1 – 1/A of the job remains uncompleted. A in this case stands for work rate.