Question

Daca a+2b+3c=100 si 3a+2b+c=140 calculati a+b+c si a-c

Answer 1

Adunand cele doua relatii obtinem:
4a+4b+4c=100+140
4(a+b+c)=240
a+b+c=240:4
a+b+c=60.

Daca din a doua relatie scadem prima relatie obtinem:
2a-2c=140-100
2(a-c)=40
a-c=40:2
a-c=20

Answer 2

a+2b+3c+3a+2b+c=100+140
4a+4b+4c=240
4(a+b+c)=240
a+b+c=60

3a+2b+c-a-2b-3c=140-100
3a+c-a-3c=40
2a+c-3c=40
2a-2c=40
2(a-c)=40
a-c=20