The sum of the cost prices of two articles A and B is Rs 26000. Both articles are sold at a profit of 20 percent and 40 percent respectively. However, the selling price of the two articles remains the same. Find the difference in the cost price of A and B.

CP of A and B differ by Rs 2000.

Equal SP means 1.2 x CP_A = 1.4 x CP_B, so CP_A/CP_B = 14/12 = 7/6.

Total parts = 7 + 6 = 13 for Rs 26000, so 1 part = 2000.

CP_A = 7 x 2000 = 14000 and CP_B = 6 x 2000 = 12000.

Difference = 14000 - 12000 = 2000.

Method: equal SP gives an inverse ratio from the profit factors.