P is a point on one side of the straight line UV and P moves in the same direction as UV. If the straight line ST is on the locus of P and angle VUS = 50°, find angle UST.
The correct answer is: B
Explanation

See Figure above.
Since ST is parallel to UV => angle< U = 50°(alternate to <S.
Angle UST = 180° - 50° = 130° (angle on a straight line)
There is an explanation video available .