The cost prices of two articles A and B are in the ratio 4:5. While selling these articles, the shopkeeper gains 10% on article A and 20% profit on article B, and the difference in their selling prices is ₹ 480. Find 30% of the total cost price (in ₹) of both the articles.

Let the cost prices be 4x and 5x (ratio 4:5). Article A: 10% gain, so SP = 4x × 1.1 = 4.4x. Article B: 20% gain, so SP = 5x × 1.2 = 6x. Difference: 6x - 4.4x = 1.6x = 480, so x = 300. Total CP = 4x + 5x = 9x = 2700. 30% of total CP = 0.3 × 2700 = 810. Option B is correct. Verification: CP_A=1200, CP_B=1500, SP_A=1320, SP_B=1800, difference=480, 30% of 2700=810.