Guys I'm having a hard time solving this geometric problem given by my teacher
Given : the figure is parallelogram
Line T to S = 42cm
Line A to C = 30cm
Line U to S = 21cm
I supposedly need to find the measure of Line B to S
but my teacher gave already the measure which is (Line B to S = 24cm)
but I need to know what is the procedure or formula on solving the measure of Line B to S
Could someone help me please?