432=60a+30b+ 18c

And a, b, c >；; = 1; A< at the same time, a < = 4；;

According to the above equation, c=4 (the right side of the equation =432, if c >；; If it is 4, it must be multiplied by 6 to ensure that the single digit is 2, which is equal to 18*4*6=432, so c can only be =4).

So the equation becomes: 360=60a+30b.

That is 36 = 6a+3b->; 12=2a+b

Let's start the discussion:

1.a=4, then b=4.

2.a=3, then b=6.

3.a=2, then b=8.

4.a= 1, then b= 10.

So there are four ways to buy a set for 3000 yuan.

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This kind of topic should list the equations first, and then analyze the range of unknown quantities.

Simplify the equation as much as possible and discuss it separately at last.