Cost price of article A is 100/more than cost price of article B. Article A was sold at 40% profit and article B was sold at 40% loss. If the overall profit earned after selling both the articles is 5%, what is the cost price of article B ?

Let cost price of article B = $$Rs. 100x$$

=> Cost price of article A = $$Rs. (100x + 100)$$

Total C.P. = $$Rs. (200x + 100)$$

Overall profit = 5%

=> S.P. = $$(200x + 100) + \frac{5}{100} \times (200x + 100) = Rs. (210x + 105)$$ --------------(i)

Article A was sold at 40% profit and article B was sold at 40% loss.

=> Selling price of article B = $$100x - \frac{40}{100} \times 100x = Rs. 60x$$

Selling price of article A = $$(100x + 100) + \frac{40}{100} \times (100x + 100)$$ = $$Rs. (140x + 140)$$

Total S.P. = $$Rs. (200x + 140)$$ -------------(ii)

Equating equations (i) & (ii), we get :

=> $$210x + 105 = 200x + 140$$

=> $$10x = 140 - 105 = 35$$

=> $$x = \frac{35}{10} = 3.5$$

$$\therefore$$ Cost price of article B = $$100 \times 3.5 = Rs. 350$$