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%.

Let the number of articles = n

Difference between the selling price of articles if sold for ₹12 instead of ₹9 = ₹150

$$=$$>  12n - 9n = 150

$$=$$>  3n = 150

$$=$$>  n = 50

Number of articles = 50

Given, Cost price of 50 articles = ₹250

$$=$$>  Cost price of 1 article = ₹5

$$=$$>  Cost price of 21 articles = 21 x 5 = ₹105

Profit% = 20%

$$\therefore\ $$Selling price of 21 articles = $$\frac{120}{100}\times105$$ = ₹126

Hence, the correct answer is Option A