Tong do dai 2 day la:
\(\frac{15}{6}\times2:\frac{4}{5}=\frac{25}{4}\left(dm\right)\)
Day lon la:
\(\left(\frac{25}{4}+\frac{2}{3}\right):2=\frac{83}{24}\left(dm\right)\)
Day be la:
\(\frac{83}{24}-\frac{2}{3}=\frac{67}{24}\left(dm\right)\)
D/s:.....
HTDT