Let's calculate the cost price (CP) and selling price (SP) for the mangoes:

Cost Price (CP) of 15 mangoes = Tk. 10 Cost Price (CP) of 1 mango = Tk. 10 / 15 = Tk. 2/3

Selling Price (SP) of 10 mangoes = Tk. 15 Selling Price (SP) of 1 mango = Tk. 15 / 10 = Tk. 3/2

Now, let's calculate the profit percentage:

Profit per mango = Selling Price (SP) per mango - Cost Price (CP) per mango Profit per mango = (Tk. 3/2) - (Tk. 2/3) Profit per mango = (3/2) - (2/3) Profit per mango = (9/6) - (4/6) Profit per mango = (5/6)

Now, calculate the profit percentage:

Profit Percentage = (Profit per mango / Cost Price per mango) * 100 Profit Percentage = [(5/6) / (2/3)] * 100 Profit Percentage = [(5/6) * (3/2)] * 100 Profit Percentage = (15/12) * 100 Profit Percentage = (5/4) * 100 Profit Percentage = 125%

So, the shopkeeper earns a profit of 125%.