回複：奧地利奧賽題：3元1次方程組（2星）

(3.1, 2.2, 5.8) or (3.6, 2.7, 4.3).
It can be proved that {c} + {b} = 1.0 and {a} + {c} =0.9, and {b} +{a} = 0.3 or 1.3.
If {c} + {b} = 0, then {c} & {b} = 0, then {a}+{c}=={b} + {a}, that is not true.
if {a} +{c} = 1.9, {c}+{b} = 1.0, then {a}=0.9+{b}, then {b}+{a}=1.3 ==> {a}=1.1, which is not true either