Answer:
800 mm or 80 cm
Explanation:
We are given that Jessica is measuring two line segments.
Length of first line segment =30 cm
Length of second line segment=300 mm
We have to find that Length of two line segments together
We know that 1 cm =10 mm
Length of firs line segment =

Length of two line segments together=500+300=800 mm=

Hence, the length of two line segments together=800 mm=80 cm