19. (6 points) A 30 cm long iron wire can form 7 different rectangles (with integer side lengths).
【Solution】Solution: The perimeter of a rectangle $=($ length + width $) \times 2$,
The sum of length and width is: $30 \div 2=15$ (cm),
Since $15=1+14=2+13=3+12=4+11=5+10=6+9=7+8$, it can form 7 different rectangles.
Answer: It can form 7 different rectangles.
Therefore, the answer is: 7.
19. (6 points) A 30 cm long iron wire can form $\qquad$ different rectangles (with integer side lengths).

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19. (6 points) A 30 cm long iron wire can form $\qquad$ different rectangles (with integer side lengths).