The value of ST is 123.8 cm.
How the length of ST is determined.
A parallelogram is a quadrilateral with opposite sides that are both equal in length and parallel.
Given
Parallelogram STUV
VU = 123.8 cm
Angle WSV = 57⁰
Diagonal SU = 108.8 cm
From the definition of parallelogram
TU = SV
Also
ST = VU
Since VU is 123.8 cm
ST = 123.8 cm
Therefore, the value of ST is 123.8 cm.