Answer:
Combine profit of 2018 and 2019 is $200 + (-$100 loss) = $100 profit.
Explanation:
The value of imported product from Germany as on 1st Dec. 2018 = 300 Euro
The exchange rate as on 1st Dec. 2018 = 0.6 Euro/Dollars
The value of imported product in dollars =
Since product sold in cash for $400 as on 15th Dec.
Since fiscal year end on 31st Dec. So, find the profit and loss.
Profit and loss = Sold price - Product price in dollars
Profit and loss = $400 - $500
Thus, loss for the year 2018 = $100
Now the dealer will pay on 1st Feb 2019 and on this date the exchange rate is 1.5 Euro/Dollars. The dealer have to pay the 300 Euro. So,on 1st Feb the value of 300 Euro in dollars will be:

Now, dealer will pay only $200 which is equal to 300 Euro. However, dealer had received $400 from sale. So. Profit is $400 - $200 = $200.
Thus, the loss of 2018 is $100 and profit of 2019 is $200.
Combine profit of 2018 and 2019 is $200 + (-$100 loss) = $100 profit.