Answer :
x - Carl's age
y - Jill's age
[tex]5x+3y=110 \\ y=2x \ \ \ |\times (-3) \\ \\ 5x+3y=110 \\ \underline{-3y=-6x} \\ 5x+3y-3y=110-6x \\ 5x=110-6x \\ 5x+6x=110 \\ 11x=110 \\ x=10[/tex]
Carl is 10 years old.
y - Jill's age
[tex]5x+3y=110 \\ y=2x \ \ \ |\times (-3) \\ \\ 5x+3y=110 \\ \underline{-3y=-6x} \\ 5x+3y-3y=110-6x \\ 5x=110-6x \\ 5x+6x=110 \\ 11x=110 \\ x=10[/tex]
Carl is 10 years old.