The donkey driver Donkey King is using a donkey to carry goods from Harbor City to a village up in the mountains. The people living in the village are willing to buy gold, silk, salt, and sponge. Donkey King is able to earn €500 for each gold bullion, €200 for each roll of silk, €150 for each sack of salt, and €100 for each sponge. There are only two bullions of gold and four rolls of silk but infinite amounts of salt and sponge. His donkey can carry 80 kg and the volume of the goods may not exceed 200 kg. The weights are: gold 1 kg/ bullion, silk 2 kg/roll, salt 25 kg/sack, and sponge 0.5 kg/each. Volumes: gold 0.1 L/bullion, silk 5 L/roll, salt 20 L/sack, and sponge 10 L/each. Help Donkey King maximize its profit for each carry.