Estimate the time to walk to school

I estimated how much time it would take to walk from home to school.

I checked it was 12 kilometres to IST, so if I walked on average 4 kilometres per hour that means for every hour I walk, I would go 4 kilometres.

If I need to go 12 kilometres - how many 4s are in 12? I divided 12 by 4 which equals 3.

Therefore I estimate it would take me 3 hours.