Investment = $5,000
Price of the product or sale price = $3.49
Production cost = $2.16
Profit = 3.49 - 2.16 = $1.33
We need to sell X items to get our investment back, therefore
X * Profit = Investment
1.33 * X = 5,000
X = 5,000 / 1.33 =3759.4
Therefore you need to sell at least 3760 articles to break even
Additionally, if you want to make a $10,000 profit, then you need to sell those items plus Y more or in other words, you want to sell as many items to get your $5,000 investment plus $10,000
This is...
5,000 + 10,000 = K * (1.33)
15,000 = 1.33 * K
K = 15,000 / 1.33 = 11,278.2 ;
Therefore, you need to sell 11,279 items