3. (5 points) Around a rectangular square that is 500 meters long and 300 meters wide, a pot of flowers is placed every 2.5 meters. Now, it is to be changed to placing a pot of flowers every 2 meters, and the flower pots at the four corners of the square will remain unchanged. Then, the number of additional pots of flowers needed is $\qquad$, and the number of pots of flowers that do not need to be moved when rearranging is $\qquad$.
【Solution】Solution: $(500+300) \times 2=1600$ (meters),
$1600 \div 2.5=640$ (pots),
$1600 \div 2=800$ (pots),
$800-640=160$ (pots);
2.5 meters $=25$ decimeters,
2 meters $=20$ decimeters,
The least common multiple of 20 and 25 is 100.
100 decimeters $=10$ meters,
$1600 \div 10=160$ (pots);
Answer: 160 more pots of flowers are needed, and when rearranging the pots, 160 pots of flowers do not need to be moved.
Therefore, the answers are: 160, 160.