A trader bought two mobiles for Rs. 39000. He sold one at a loss of 20% and the other at a profit of 15%. If selling price of each mobile is the same, then their cost price are respectively.

Let cost prices be x and y with x + y = 39000. Selling at 15% profit: 1.15x. Selling at 20% loss: 0.8y. Since selling prices are equal: 1.15x = 0.8y, so y = (1.15/0.8)x = 1.4375x. Substituting: x + 1.4375x = 39000, so 2.4375x = 39000, x = 16000. Then y = 23000. The cost prices are Rs. 23000 and Rs. 16000 respectively. Therefore, option D is correct.