[tex]\displaystyle\\
4+ \frac{7}{10} + 8+ \frac{1}{5} = \\\\
=4+8+ \frac{7}{10} + \frac{1}{5} = \\
\text{ Adunam intregii si amplificam fractia a 2-a cu 2. }\\
=12+ \frac{7}{10} + \frac{2}{10} = \\\\
=12 + \frac{7+2}{10} =12 + \frac{9}{10} = \boxed{\bf 12\frac{9}{10}~metri}
[/tex]
