Question 244500
In t years the man will be 30 + t years old
in t years the son will be 4+t years old.
in t years the man (30+t)   will be twice 2* as old as the son (4+t) 



30+t=2(4+t)
30+t=8+2t
subtract 8 from both sides 
22+t=2t=t+t
and subtract t from both sides
22=t
In 22 years the man will be 52 and the son will be 26.