The difference between the selling prices of some articles if sold for ₹12 instead of ₹9 is ₹150. If the cost price of these articles is ₹250, then find the selling price of 21 articles if profit earned is 20%.

₹126

According to the question,

Let the number of article be x.

Selling price at Rs. 12 per article – Selling price at Rs. 9 per article = 150

= 12x – 9x = 150

= 3x = 150

= x = 50

Cost price per article = Total cost price/Number of article

Cost price per article = 250/50

Cost price per article = Rs. 5

Selling price = Number of article × Cost price × (100 + profit %)/100

= 21 × 5 × (100 + 20)/100

= 105 × 120/100 = 126