If there are two bottles 5 and 7 liters how to make 6 liters?

Fill the 5l bottle Pour the 5l into the 7l bottle Fill the 5l bottle Pour 2l from the 5l bottle to the 7l bottle, leaving 3l in the 5l bottle Empty the 7l bottle Pour the 3l into the 7l bottle Fill the 5l bottle Pour the 5l into the 7l bottle leaving 1l in the 5 ll bottle Empty the 7l bottle Pour the 1l into the 7l bottle Fill the 5l bottle Pour the 5l bottle in the 7l bottle which makes 6l in the 7l bottle! Hard work for just 6l!