Answer:
30% of Ariana's serves were aces.
Explanation:
Since a percentage is essentially (part / whole) * 100, we can determine what percent of Ariana's serves were aces by multiplying 15/50 by 100:
Percentage of aces = (15/50) * 100
Percentage of aces = (3/10) * 100
Percentage of aces = 300/10
Percentages of aces = 30
Thus, 30% of Ariana's serves were aces.