Răspuns :
2a+b+2c=25
a+b+c=18
-------------(+)
3a+2b+3c=25+18=43
2a+b+2c=25
a+b+c=18
--------------(-)
a+c=25-18=7
(a+c)*(3a+2b+3c)=7*43=301
a+b+c=18
-------------(+)
3a+2b+3c=25+18=43
2a+b+2c=25
a+b+c=18
--------------(-)
a+c=25-18=7
(a+c)*(3a+2b+3c)=7*43=301
adunam cele 2 relatii si obtinem 3a+2b+3c=18+25=43 din prima relatie⇒b=18-a-c inlocuim b in a 2 a relatie si ⇒2a+18-a-c+2c=25⇒a+c+18=25⇒a+c=25-18=7 deci ,7×43=301