Let the cost of 1 kg of apple be x and cost of 1 kg of grape be y.

Given, cost of 2 kg of apples and l kg of grapes on a day was found to be Rs 160.

∴ 2x + y = 160

After 1 month, let the cost of 1 kg of apple be x and cost of 1 kg of grape be y

Also, after a month, the cost of 4 kg of apples and 2 kg of grapes is Rs 300.

∴ 4x + 2y = 300