Given parameters:
Cost price of the article = Nu.28.30
Selling price of the article = Nu.29.30
Unknown:
Gain percentage = ?
The gain percentage is the same as the percentage profit on a trade.
The formula is given as:
Gain percentage =

Profit = Selling price - Cost price
= Nu.29.30 - Nu.28.30
= Nu. 1
Now input the parameters and solve;
Gain percentage =

= 3.5%
The gain percent is 3.5%