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Junior high school mathematics problem solving
Solution: (1) Suppose that X million bricks A and Y million bricks B are produced (both X and Y are positive integers); Judging from the meaning of the question.

x+y=30

4.5x+2y≤ 1 15

1.5x+5y≤80

Establish a coordinate system with O (0 0,0) as the origin, as shown in the figure. The feasible solution region is a triangle surrounded by graphs, where the feasible solution is

(20, 10),(2 1,9),(22,8)

So, there are three production schemes.

(2) Let the total cost be W, then

w= 1.2x+ 1.8y

? =54? -? 0.6 times

Therefore, the greater the x, the smaller the total cost, so take x = 22.

W=40.8 at this time.

220,000 A bricks and 80,000 B bricks were produced, and the lowest cost was 408,000 yuan.