Explicație pas cu pas:
P = 7 m
[tex]l = \frac{P}{4} = \frac{7 \: m}{4} = 1.75 \: m = 17.5 \: dm = 175 \: cm \\ [/tex]
P = 30 dm
[tex]l = \frac{P}{4} = \frac{30 \: dm}{4} =7.5 \: dm = 0.75 \: m = 75 \: cm \\ [/tex]
P = 200 cm
[tex]l = \frac{P}{4} = \frac{200 \: cm}{4} =50 \: cm = 5 \: dm = 0.5 \: m \\ [/tex]