let s be Seth's age. let r be Romans age. 5 years ago Seth was s-5 and Roman was three times as old, or 3(s-5), or 3s-15=r-5
in ten years Seth will be s+10 and Roman will be twice as old, or 2(s+10), or 2s+20=r+10
3s-15 =r-5
r=3s-10
2s+20=r+10
r=2s+10
3s-10=2s+10
s=20
Seth is 20 years old
setting the two equations equal gives us
3(s-5)=2(s+10)
3s-15=2s+20
s=35
