Answer: Liam leave 4 hours before his parents.
Step-by-step explanation:
Let the speed of Liam be x
Let the speed of Liam's parents be 3x
In 2 hours, his father caught him,
Distance covered by his father = 2(3x)=6x
Total time of Liam covered 6x distance in (t+2) hours.
According to question,
[tex]6x=x(t+2)\\\\6=t+2\\\\t=6-2=4\ hours[/tex]
Hence, Liam leave 4 hours before his parents.
