a trader bought a number of articles.

Answer to your question "a trader bought a number of articles for Rs 900, five were damaged and he sold each of the rest at Rs 2 more than what he paid for it, thus getting a profit of Rs 80 on whole transaction. find the number of articles he bought' is as follows

let the trader bought x toys

Total price paid =900 so the CP of each artical will be 900/x

ATQ SP of each toy will be 900/x+2

Since 5 toys were damaged in the transaction so the remaining toys were x-5

Total SP will be (x-5)(900/x+2)

profit is 80 so SP -CP =80

(x-5)(900/x+2)=980

simplifying we will have 2x²-90x-4800 =0

solving the quadratic we will have x =75