19)
Notăm:
m-vârsta lui Mihai;
g- vârsta Geaninei.
[tex]\it m+g=24\ \ \ \ \ (1)\\ \\ m>g\ cu\ 6\ \Rightarrow\ m=g+6|_{+m}\ \Rightarrow\ m+m=m+g+6 \stackrel{(1)}{\Longrightarrow}\ 2m=24+6\Rightarrow\\ \\ \Rightarrow 2m=30 \Rightarrow m=15\ \ \ \ \ (2)\\ \\ (1),\ (2) \Rightarrow 15+g=24 \Rightarrow g=24-15 \Rightarrow g=9[/tex]
Deci, Mihai are 15 ani, iar Geanina are 9 ani.
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Metoda figurativă:
g |______|
} = 24
m |______| + 6
24 - 6 = 18 (cele două segmente egale)
18 : 2 = 9 (un segment)
Geanina are 9 ani.
Mihai are 9+6 = 15 ani
