Respuesta :
Answer:
B. 90
Step-by-step explanation:
Since the two angles are supplementary, this means they both are on a flat line (180 degrees)
Since both A and B add up to 180, we take that number and subtract A (90) to get our answer: 90 degrees
B.90 if angles are supplementary that means they add up to 180 degrees and 90 plus 90 is 180