Răspuns :
m+n=40 ⇒ 2m+2n=80
n+p=60 ⇒ 2n+2p=120
2m+4n+2p=80+120
2m+4n+2p=200
n+p=60 ⇒ 2n+2p=120
2m+4n+2p=80+120
2m+4n+2p=200
m+n=40|*2
n+p=60|*2
2m+2n=80
2n+2p=120
Adunam cele doua relatii
2m+4n+2p=200
n+p=60|*2
2m+2n=80
2n+2p=120
Adunam cele doua relatii
2m+4n+2p=200