3x+5(48-x)≤200

3x+240-5x≤00

2x≥40

x≥20

48-x≥x

x≤24

So the value range of x is 20≤x≤24.

The immediate purchase scheme is as follows:

1, pen: 20, notebook 28

2. Pen: 2 1, notebook 27

3. Pen: 22, notebook 26

4. Pen: 23, notebook 25

5. Pens: 24, notebooks: 24

Finally.

X=20, y=28, that's 200 yuan.

X = 2 1, y=28, total 198.

X=22, y=26, and the total money is 196.

X=23, y=25, and the total money is 194.

X=24，y=24。 The total amount of money is 192.

Is that enough? 24 pens and 24 notebooks are the most economical.

Minimum cost 192 yuan.