The Solution:

The key to this puzzle is focusing on your total profit, not the individual transactions. We can calculate this by subtracting your total spending on the cow from your total earnings from selling it.

Total spent on the cow: $800 (first purchase) + $1100 (second purchase) = $1900
Total earned from selling the cow: $1000 (first sale) + $1300 (second sale) = $2300
Now, subtract your total spending from your total earnings to find your profit:

 

Profit = $2300 (earned) – $1900 (spent) = $400
Therefore, you made a profit of $400 overall.