Sally's brother Aaron is 15 years old...

Sally's brother Aaron is 15 years old. Carl is 8 years older than Aaron and the sum of their ages is 47 years. How old is sally? Show full algebraic working.

$$\small{\text{$ \begin{array}{rcl} \rm{Aaron~is~15~years~old}\\\\ \rm{Carl~=~8~years + Aaron}= 8 + 15 \\ \rm{Carl~is~23~years~old~}\\\\ \rm{Sally+Carl+Aaron}=47\\ \rm{Sally~}+23+15=47\\ \rm{Sally~}+38=47\\ \rm{Sally~}=47-38\\ \rm{Sally~}=9\\ \rm{Sally~is~9~years~old~} \end{array} $}}$$