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A+b=857
A-b=343
A?
B?


Răspuns :

a+b=857
a-b=343
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2a / =1200
a=1200:2
a=600
b=857-600=257
b=257
a+b=857
a-b=343
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2a=1200 => a =1200:2= 600
600+b=857 => b=857-600= 257