notam: x merele Oanei
y merele Clarei
merele Oanei + 3 mere =
merele Clarei – 3 mere
de doua ori (merele Oanei -2
mere)= merele Clarei +2 mere
x+3=y-3 => y=x+6
2(x-2)=y+2, il inlocuim pe y
=> 2x-4=x+6+2
2x-x=8+4
x=12 (mere are Oana)
y=x+6=12+6
y=18 (mere are Clara)
R: Oana are 12 mere, Clara
are 18 mere
verificare: 12+3=18-3 (adevarat)
2(12-2)=18+2
2·10=20 (adevarat)