The man buys 300 articles at 4 for $6, which means that he pays:
$6 for every 4 articles, or $1.50 per article.
The man then sells all 300 articles at $2 each, which means that he earns:
$2 for every article.
To find the man's profit, we need to subtract his cost from his revenue. His cost is the amount he paid for the 300 articles, which is:
300 articles * $1.50 per article = $450
His revenue is the amount he earned from selling the 300 articles, which is:
300 articles * $2 per article = $600
So his profit is:
$600 - $450 = $150
To find the profit made by the man on selling one article, we can divide his total profit by the number of articles he sold:
$150 / 300 articles = $0.50 per article.
Therefore, the man's profit on selling one article is $0.50