The time on the clock is
[tex]1\colon00[/tex]
The time it will be in 1 hours will be
[tex]1\colon00\text{ +1hour= 2:00}[/tex]
The time it will be 3 hours 30 minutes ago will be
[tex]1\colon00-3h\text{ 30 minutes= 9:30}[/tex]
The time it will be in 1 hour 30 minutes will be
[tex]1\colon00-1h\text{ 30 minutes=2:30}[/tex]
