We can represent the given question as follow
Let one piece of be = x, then the other part will be = x+30
Thus
[tex]\begin{gathered} x+(30+x)=70 \\ \text{simplifying} \\ x+30+x=70 \\ 2x+30=70 \\ 2x=70-30 \\ 2x=40 \end{gathered}[/tex]Hence
[tex]\begin{gathered} x=\frac{40}{2}=20 \\ x=20 \end{gathered}[/tex]One length is 20cm
The other one will be 20cm+30cm =50 cm
Thus
20cm and 50cm are the lengths of the piece
