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Solution: Suppose you need to burn X discs, then

It takes y 1=8x to burn in a computer company.

Y2= 120+4x is used for automatic recording.

When y 1=y2, 8x= 120+4x,

The solution is x = 30.

When y1"y2,8x"120+4x,

The solution is x》30；;

When y1y2,8x120+4x,

Solve x "30.

Therefore, when you need to burn 30 CDs, the cost of burning and self-engraving in a computer company is equal;

When more than 30 discs need to be burned, the cost of self-recording is saved;

When you need to burn no more than 30 CDs, you can save money by burning in a computer company.