If Aaron is 15 years old, and his sister is 3 times as old as him, then the sister is 3*15 = <<15*3=45>>45 years old.
Together, Aaron and his sister have a total age of 45+15 = <<45+15=60>>60 years
Henry is four times as old as the sister, meaning he is 45*4 = <<45*4=180>>180 years old.
The three siblings together have a total age of 60+180 = <<60+180=240>>240 years
#### 240