Anew phone sells for $250 and a used one sells for $75. how many of each are sold if the profit for the day is $625?

1 new and 5 used

Step-by-step explanation:

If we subtract multiples of 250 from 625 and divide by 75, we can determine the number of phones.  

We know that 250(2) = 500; if we subtract this from 625, this leaves

625-500 = 125 for the old phones.  Dividing this by 75, we see that it is not a whole number; this means there cannot have been two of the new $250 phones sold.

625-250 = 375.  Dividing this by 75, we get 5; this means 1 new phone and 5 old were sold.

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