Răspuns :
a+2b+4c=98
b+c=22
a+c=42
___________
a+c=42
=> c=42-a
b+c=22
=> b=22-c
=> b=22-42-a
=> b= -20-a
a+2b+4c=98
=> a+2(-20-a)+4(42-a)=98
=> a-40-2a+168-4a=98
=> a-2a-4a=98-168+40
=> -5a= -30
=> a= -30/-5
=> a= 6
a+c=42
=> 6+c=42
=> c=42-6
=> c=36
b+c=22
=> b+36=22
=> b=22-36
=> b= -14
Răspuns:
a=6
b= -14
c=36