Quantity = total water consumption, just establish an equation and find its solution; ?
(2) Assuming that the average annual water consumption of urban residents is Z cubic meters, the goal can be achieved. Similarly, from the equivalent relationship of water storage +25-year precipitation = 200,000 people's 25-year water consumption, the equation can be established and solved.
Answer:? Solution: (1) Suppose that the annual precipitation is X million cubic meters and the per capita annual water consumption is Y cubic meters, which was put forward by him.
12000+20x= 16×20y，
12000+ 15x = 20× 15y
X=200，y=50。
A: The annual precipitation is 2 million cubic meters, and the per capita annual water consumption is 50 cubic meters.
(2) If the average annual water consumption of urban residents is Z cubic meters, the goal can be achieved.
The meaning of the question is 12000+25×200=20×25z, and the solution is: z=34 is 50 ~ 34 = 16 (cubic meter).
A: Urban residents need to save 16 cubic meters of water every year to achieve this goal.
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