David purchased some cookies at the cost of 5 for $4 and sold them at 4 for $5. david made a profit of $180 in total. how many cookies did david purchase to make that much money?

David purchased some cookies at the cost of

5 for $4 (5/4=1.25) and

sold them at 4 for $5(4/5=0.80).

To find cost per cookie subtract 1.25-0.80=0.45

David made a profit of $180 in total ( divide profit per cookie cost: 180/0.45= 400)

How many cookies did David purchase to make that much money?

He needed to make 400 cookie to make the profit of $180.

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