IP-Modelling and Xpress-MP

I had a hard time understanding this problem. Could you please explain the IP-Model and Xpress solution step by step?

1 Making Riches with Ali Baba After keeping Ali Baba in the cave for a few days, the thieves decide to release him. Ali Baba tells the thieves that he wants to get some gold coins from the cave In response, the thieves give Ali Baba an aseagnment and say that he can get a certain number of gold coins from the cave, according to the result of this assignment. In the beginning, the thieves give Ali Baba a 77 chessboard without any coins on it. According to the rules of the assignment, Ali Babo will leave as many unit squares of this cheseboard as be wants empty, and place either a gold or a bronze coin in each of the remaining unit squares. According to the rules of the assignment, any 33 square of unit squares of the chessboard must contain an equal number of gold and bronze coins after all the coins have been placed. According to the agreement, after the coins are properly placed by Ali Baba, the theves allow Ali Baba to take awzy all the gold coins from the 77 chesbobard. Figure 1: Example 33 grids 2 Questions 1. Formulate an IP-Model for Ali Baba's assignment to maximize his profit. 2. Solve your model using XPress-MP. Briefly explain your results. 3. (Bonus) How would you solve the same problem if instead of 77,901000 90000 ches board was given? What is the guarantee that your approseh will be optimal ? 1 Making Riches with Ali Baba After keeping Ali Baba in the cave for a few days, the thieves decide to release him. Ali Baba tells the thieves that he wants to get some gold coins from the cave In response, the thieves give Ali Baba an aseagnment and say that he can get a certain number of gold coins from the cave, according to the result of this assignment. In the beginning, the thieves give Ali Baba a 77 chessboard without any coins on it. According to the rules of the assignment, Ali Babo will leave as many unit squares of this cheseboard as be wants empty, and place either a gold or a bronze coin in each of the remaining unit squares. According to the rules of the assignment, any 33 square of unit squares of the chessboard must contain an equal number of gold and bronze coins after all the coins have been placed. According to the agreement, after the coins are properly placed by Ali Baba, the theves allow Ali Baba to take awzy all the gold coins from the 77 chesbobard. Figure 1: Example 33 grids 2 Questions 1. Formulate an IP-Model for Ali Baba's assignment to maximize his profit. 2. Solve your model using XPress-MP. Briefly explain your results. 3. (Bonus) How would you solve the same problem if instead of 77,901000 90000 ches board was given? What is the guarantee that your approseh will be optimal