Answer:
4 units
Step-by-step explanation:
[tex] \because \: l = \frac{ \theta}{360 \degree} \times c \\ \\ \therefore \: l = \frac{72 \degree}{360 \degree} \times 20 \\ \\ \therefore \: l = \frac{72 \degree}{18\degree} \\ \\ \therefore \: l = 4 \: units[/tex]
