posted by Anonymous .
John's father is thrice as old as John. 6 years from now, his father will be 24 years older than John. How old is John now?
"I think we can say that the father is 24 years older than John, regardless of how old they are. If J represents John's age now, then 3J represents John's father's age. This is equal to J+24, so we set an equation
3J = J + 24
2J = 24
J = 12, 3J = 36
John is 12, and his father is 36."