We know she counted 24 red jelly beans and 18 white jelly beans so 24 + 18 = <<24+18=42>>42 jelly beans
Even though she only bought 1 bag of jellybeans, she thought it would take 3 bags to fill up the bowl. So 3 bags * 42 jellybeans = <<1*42+1*42+1*42=126>>126 total red & white jellybeans
#### 126