Question 1182625
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@greenestamps has the right idea, but made a typo for the range. 


The range should be {1800, 1820, 1840, ..., 4580, 4600}


The 4400 he wrote should be 4580. Other than that, it's correct.


The range consists of possible values of P, ie possible payments she earns. 


Notice that P increases by 20. This is due to the slope being 20.
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