First, you would have to set up an equation. I made it so J=Joes, A=Aaron and C=Chris. The first equation is J=3A, and A-6=C. If J+A+C=149, then you can use substitution to find A. (3A)+A+(A-6)=149, then simply solve for A. I got A=28.6. Then, you can substitute 28.6 for A in the first two equations, making it J=3(28.6) and 28.6-6=C. So, Chris's age is 22 years and 7 months, Joes age is 85 years and 8 months, and Aaron's age is 28 years and 7 months.