Question

Afla nunerele a b c stiind ca sunt verificate simultan relatiile
a+b=12
b+c=13
a+c=15

Answer 1

a+b+b+c+a+c=12+13+15
2x( a+b+c)=40
a+b+c=40:2
a+b+c=20
a+b=12
12+c=20
c=20-12
c=8
b+c=13
b+8=13
b=13-8
b=5
a+c=15
a+8=15
a=15-8
a=7