Problem:
How many kg of 50 per kg should be mixed with 35 Bank ke costing rupees 64 kg 2 as to sell the mixture at 57 kg without any gain or loss?

Solution:

To solve this problem, we need to determine the quantity of 50 per kg that should be mixed with the 35 Bank ke costing rupees 64 kg 2 in order to obtain a mixture weighing 57 kg without any gain or loss.

Step 1: Calculate the total cost of the 35 Bank ke:
The cost of 1 kg of Bank ke is given as 64 rupees. Therefore, the cost of 35 kg would be:

Cost of 35 Bank ke = 35 * 64 = 2240 rupees

Step 2: Calculate the total cost of the mixture:
Since we want to sell the mixture without any gain or loss, the total cost of the mixture should be equal to the total cost of the 35 Bank ke.

Total cost of the mixture = 2240 rupees

Step 3: Determine the cost of the 50 per kg:
We know that the cost of the 50 per kg is 50 rupees per kg.

Step 4: Determine the quantity of the 50 per kg:
Let's assume the quantity of the 50 per kg that needs to be mixed is 'x' kg.

Cost of the 50 per kg = 50 * x rupees

Step 5: Set up the equation:
Since the total cost of the mixture should be equal to the total cost of the 35 Bank ke, we can set up the following equation:

50 * x = 2240

Step 6: Solve the equation:
Solving the equation, we find:

x = 2240 / 50
x = 44.8 kg

Therefore, 44.8 kg of the 50 per kg should be mixed with the 35 Bank ke costing rupees 64 kg 2 in order to obtain a mixture weighing 57 kg without any gain or loss.

Answer:
44.8 kg of the 50 per kg should be mixed with the 35 Bank ke costing rupees 64 kg 2 to sell the mixture at 57 kg without any gain or loss.