The two angles, when added, should form a straight line.
A. ∠RST and ∠RSV form the line VT
B. ∠RST and ∠TSU form the line RU
C. ∠RST and ∠VSU form opposite angles with each other
D. ∠TSU and ∠USV form the line VT
E. ∠TSU and ∠RSV form opposite angles with each other
So, the answers are A, B and D.
