The average cost price of articles 'C' and 'D' together is

Solution

ATQ,

Let the cost price of article 'C' = Rs. '10x'

Then, cost price of article 'D' = Rs. (10x + 40)

Sum of cost price of articles 'C' and 'D' = 10x + 10x + 40 = Rs. (20x + 40) = 350 × 2

Or, 20x + 40 = 700

Or, 20x = 660

Or, x = 33

Cost price of articles 'C' and 'D' are Rs. 330 and Rs. 370, respectively

Selling price of article 'C' = 330 × 1.18 = Rs. 389.4

Selling price of article 'D' = 370 × 1.22 = Rs. 451.4

Required difference = 451.4 - 389.4 = Rs. 62