Răspuns :
Notam Ana=>a
Bogdan=>b
Calin=>c
a+b=7
a+c=8
a+b+c=12
c=(a+b+c)-(a+b)
c=12-7
c=5
a=8-c
a=8-5
a=3
R:Ana are 3 mere
Bogdan=>b
Calin=>c
a+b=7
a+c=8
a+b+c=12
c=(a+b+c)-(a+b)
c=12-7
c=5
a=8-c
a=8-5
a=3
R:Ana are 3 mere
A+B = 7 si
A+C = 8 aduam ....
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A+A+B+C=15 <=> A+ 12 = 15
=> A=3
A+C = 8 aduam ....
---------------
A+A+B+C=15 <=> A+ 12 = 15
=> A=3