Răspunsuri

2014-08-05T11:46:04+03:00
a+b=2 => a=2-b
b+c=5 => c=5-b
 
2a+5b+3c
2(2-b)+5b+3(5-b)=
4-2b+5b+15-3b=
4+15+5b-2b-3b=
19+5b-5b=
19