[tex]\displaystyle{ \frac{1}{2} \cdot x = 80 }[/tex]
Metoda 1
[tex]\displaystyle{ \frac{x}{2} = 80 }[/tex]
[tex]\displaystyle{ x = 2 \cdot 80 }[/tex] (se inmultesc mezii cu extremii, pe diagonala)
[tex]\boxed{x=160}[/tex]
Metoda 2
[tex]\displaystyle{ x \cdot \frac{1}{2} = 80 }[/tex]
[tex]\displaystyle{ x = 80 : \frac{1}{2} }[/tex]
[tex]\displaystyle{ x = 80 \cdot \frac{2}{1} }[/tex]
[tex]\boxed{x=160}[/tex]
