Mary bought a handbag if N15.00. If she sold it for N18.00, what is her percentage gain

To calculate the percentage gain, we need to first find the profit made by Mary.

Profit = Selling price - Cost price
Profit = N18.00 - N15.00
Profit = N3.00

Now, we can calculate the percentage gain using the following formula:

Percentage gain = (Profit/Cost price) * 100

Substituting the values we have:

Percentage gain = (N3.00/N15.00) * 100
Percentage gain = 20%

Therefore, Mary's percentage gain is 20%.