请教一道二级notes上的例题(financial reporting and analysis)，跪谢！

09年notes Book2 finacing reporting 第237页例题Part B 的部分.给你Income statement:

Sales 38000

COGS  -24000

Depreciation expense  -3000

SG&A expense  -2000

Interest expense  -2400

Taxes -2880

Nei Income  3720

之后它怎么算出来 cash from operations=5640

cansh from investing= -4600

 cash from financing= - 640?

Thanks a lot ! 实在是想不明白!,郁闷死我了！