Charles total profit is $78.
Profit is equal to revenue - cost. So we need to find the difference of the money he takes in and the money he paid.
First, we find how much he paid.
Then, we find how much he made. Subtracting these two gives us the answer.
He paid for 30 packs of pens at $4.60 each, which amounts to $138.
He had a total of 450 pens and sold 3/5 of them. This means he sold 270 pens. He sold them for $0.80 each, meaning he made $216.
$216-$138 = $78
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