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One's income is 120 yuan / day, and he spends his daily income on X and Y commodities. Its utility function is u = XY. The price of X is 20 yuan per unit, and the price of Y is 30 yuan per unit. Q: (1)How much do you buy commodity X and Y each day to maximize its utility? (2)If x's price goes up 44% and Y's price stays the same, how much more revenue will he have to increase to maintain his initial utility level?