If 80% of total articles are sold at a loss of 15% and remaining articles are sold at a profit of 15%, then what will be the overall loss percentage?

Let the total number of articles be 100 and the cost price of each article be Rs 1.
Total Cost Price (CP) = Rs 100.

According to the question:

80% of articles = 80 articles.
Loss on these articles = 15%
Selling Price (SP
1
​
) = 80×(1−0.15)=80×0.85=Rs 68

Remaining articles = 100−80=20 articles.
Profit on these articles = 15%
Selling Price (SP
2
​
) = 20×(1+0.15)=20×1.15=Rs 23

Total Selling Price (SP) = SP
1
​
+SP
2
​
=68+23=Rs 91

Overall Loss = CP−SP=100−91=Rs 9

Overall Loss Percentage=
100
9
​
×100=9%