Each wall is 2*3=<<2*3=6>>6 square meters
So each wall takes 6*10=<<6*10=60>>60 minutes to paint
So it takes 60/60=<<60/60=1>>1 hour to paint each wall
That means in total it takes 5*1=<<5*1=5>>5 hours to paint
So he has 10-5=<<10-5=5>>5 hour left after finishing painting
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