The total cost price of a certain number of identical aricles is Rs.4,800. By selling the articles at Rs. 100 each. a profit equal to the cost price of 15 articles is made. Find the number of articles bought.
By selling an article at 20%. discount. a shopkeeper gains 25%. If the selling price of the article is Rs. 1.440; find: (i) the marked price of the article. (ii) the cost price of the article.