a+a+a一b一b=8.2 b+b+b一a一a=1.7
3a-2b=8.2 3b-2a=1.7
6a-4b=16.4 9b-6a=5.1
5b=21.5
b=4.3
3a-8.6=8.2
3a=16.8
a=5.6