If I sell a computer at $80\%$ of its marked price, I make a loss of $12\%$. What $\%$ profit will I make if the computer is sold at $95\%$ of its marked price ?

Let the marked price of Computer be M and the cost price of the Computer be 100.
therefore, the loss incurred when selling at 0.8M = 12% of 100 = 12.
Hence, when selling at 80% of the marked price, the article is sold at 100 - 12 = 88.
i.e., 0.8M = 88. or M = 110 [ Market Price = 110 ]

If the computer is sold at 95% of the marked price, I will sell the computer at 95% of 110 = 104.5
i.e. profit of 4.5%