Analysis: As Mr. Zhang has two stamps with a face value of 50 cents and 80 cents respectively, these stamps can be combined to pay six different postage:

Because 50+50= 100, 80+80= 160, 50+80= 130, 50+50+80= 180 and 50+80 = 20.

Answer:

Solution: Because 50 and 80 stamps can be combined into:

50+50= 100 (minutes),

80+80= 160 (minutes),

50+80= 130 (minutes),

50+50+80= 180 (minutes),

50+80+80=2 10 (point),

50+50+80+80=260 (minutes),

Six different postage rates,

Add 50 cents and 80 cents,

* * * can pay 6+2=8 different postage.

So the answer is: 8.

Comments: You should pay attention to two stamps with 50 points and 80 points, not two stamps with 80 points and 50 points.

If you have any questions, you can ask.