On her birthday, Avianna bought red candles and blue candles in the ratio of 5:3. If Avianna had 45 red candles on her birthday, how many blue candles did she have? Let's think first. Chain of thought:
If the ratio of red candles to blue candles Avianna bought was 5:3, then the total ratio was 5 + 3 = 8. If 5 represented 45 candles in the total ratio, then 8, the actual ratio, represents 8 * 45 = 360 divided by 5 is 360 / 5 = 72 candles. If the total number of candles was 72, then the number of blue candles is 72 candles - 45 candles = 27 candles.
Therefore, the answer is 27.