Answer: [tex]\dfrac{4}{5}\ m[/tex]
Step-by-step explanation:
Given
The length of one piece of string is [tex]\frac{1}{5}\ m[/tex]
So, the length of 4 pieces is the addition of four-piece length.
[tex]\Rightarrow L=\dfrac{1}{5}+\dfrac{1}{5}+\dfrac{1}{5}+\dfrac{1}{5}\\\\\Rightarrow L=4\times \dfrac{1}{5}\\\\\Rightarrow L=\dfrac{4}{5}\ m[/tex]