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2014-10-14T14:42:58+03:00
A+b+c=18
2a+b+2c=25

(a+c)*(3a+2b+3c)=
=(a+c+a+b+c-a-b-c)*(a+2a + b+b + c+2c)=
=[(2a+b+2c)-(a+b+c)]*[(2a+b+2c)+(a+b+c)]=
=(25-18)*(25+18)=
=7*43=
 =301
1 5 1