Answer:
93 cm
Explanation:
You want to know the length of median RD if the distance from midpoint R to the centroid L is 31 cm.
Centroid
The centroid is located 1/3 the distance from the side of the triangle to the opposite vertex. Here, that distance is 31 cm, so the full length of the median is ...
3 × 31 cm = 93 cm . . . . length of RD