In the diagram, ∠RTS and ∠STU are supplementary. What is the value of x and what is the measure of ∠QTR? A. x = 15; m∠QTR = 30° B. x = 30; m∠QTR = 60° C. x = 15; m∠QTR = 60° D. x = 30; m∠QTR = 30°