b/(a+c)=1/2,a/(b+c)=1/5 怎么得出a/(a+b+c)=1/6,b/(a+b+c)=1/3?b/(a+c)=1/2,a/(b+c)=1/5 怎么得出a/(a+b+c)=1/6,b/(a+b+c)=1/3?

b/(a+c)=1/2,a/(b+c)=1/5 怎么得出a/(a+b+c)=1/6,b/(a+b+c)=1/3?b/(a+c)=1/2,a/(b+c)=1/5 怎么得出a/(a+b+c)=1/6,b/(a+b+c)=1/3?
b/(a+c)=1/2,a/(b+c)=1/5 怎么得出a/(a+b+c)=1/6,b/(a+b+c)=1/3?
b/(a+c)=1/2,a/(b+c)=1/5 怎么得出a/(a+b+c)=1/6,b/(a+b+c)=1/3?

b/(a+c)=1/2,a/(b+c)=1/5 怎么得出a/(a+b+c)=1/6,b/(a+b+c)=1/3?b/(a+c)=1/2,a/(b+c)=1/5 怎么得出a/(a+b+c)=1/6,b/(a+b+c)=1/3?
2b=a+c ...(1)
5a=b+c ...(2)
(1)-(2)得 2b-5a=a-b 6a=3b 2a=b ...(3)
上式代入(1)得 4a=a+c c=3a.(4)
所以a/(a+b+c)=a/(a+2a+3a)=1/6
b/(a+b+c) =2a/(a+2a+3a)=1/3

b/(a+c)=1/2,a/(b+c)=1/5
取倒数得：
(a+c)/b=2,(b+c)/a=5
因为1/[a/(a+b+c)]=(a+b+c)/a=1+(b+c)/a=1+5＝6
所以：a/(a+b+c)=1/6
同理可得：b/(a+b+c)=1/3