A shopkeeper purchased 30 articles for Rs. 100 each. 1 article was damaged and thrown away. The remaining were sold at Rs. 120 each. Find profit or loss %.

No. of articles = 30, Cost of each article = Rs 100
Total cost price = 30 × 100 = Rs 3000
1 of them was discarded so, only (30 -1) = 29 articles were sold at a rate of Rs 120 per article.
Total selling price = 29 × 120 = Rs 3480.

Total selling price > Total Cost price

Profit = Total selling price - Total Cost price.
Profit = Rs 3480 - Rs 3000 = Rs 480.

$\mathrm{Profit}\%=\frac{\mathrm{Profit}}{\mathrm{Cost} \mathrm{price}}\times 100$

$\mathrm{Profit}\%=\frac{480}{3000}\times 100$

$\mathrm{Profit}\%=16\%$.