[tex]ex.5[/tex]
[tex]x + x + 2x = 60[/tex]
[tex]x = 15[/tex]
[tex]ex.6[/tex]
[tex]15 \times 15 \times 30 = > \\ 225 \times 30 = > \\ 6750 \: cm[/tex]
[tex]l = \frac{72}{8} \\ 72 \div 8 = > \\ 9[/tex]
[tex]p = 4 \times l = > \\ 4 \times 18 = > \\ 72 \: cm[/tex]
