Let the number of participants in the math contest be x.

Composition proportion formula

(X-320):(8/7X-320)=3:2

X=5 12

Number of participants in China: 5 12*8/7=448 (person)

Results: 5 12+448=960 (person)

Step 2: Solutions

There are 200 pots of orchids in the Botanical Garden, so water lilies = 200× 9/40 = 45 pots.

Then roses = 45× 25/3 = 375 pots.

Then chrysanthemum = 375× 3 1/5 = 2325 pots.