Answer:Gary-18 brother-10
Step-by-step explanatiation:Gary=8 years+ brother's years
6 years ago :
Gary=3×brother's years
So:
1st case:brother=1 year,gary=3 years=>after 6 years brother=7 years,gary=9 years (NO)
2nd case:brother=2years,gary=6 years=>after 6 years brother=8 years,gary=12 (no)
3rd case:brother=3 years,gary=9 years=>after 6 years:brother=9 yrs, gary=15 yrs(no)
4th case:brother=4 yrs,gary=12 yrs=>after 6 years: brother=10 years,gary=18 years (This is the one)