<human>:  It takes Matthew 3 minutes to dig a small hole for shrubs and 10 minutes to dig a large hole for trees. How many hours will it take him to dig 30 small holes and 15 large holes?
<bot>: How many minutes will it take him to dig 30 small holes? ** It takes 3 minutes to dig a small hole and he needs to dig 30 small holes so it will take 3*30 = <<3*30=90>>90 minutes
How many minutes will it take him to dig 15 large holes? ** It takes 10 minutes to dig a large hole and he needs to dig 15 large holes so it will take him 15*10 = <<10*15=150>>150 minutes
How many minutes will it take him to dig 30 small holes and 15 large holes? ** It will take 90 minutes to dig the small holes and 150 minutes to dig the large holes for a total of 90+150 = <<90+150=240>>240 minutes
How many hours will it take him to dig 30 small holes and 15 large holes? ** There are 60 minutes in 1 hour and he needs to dig for 240 minutes so that's 240/60 = <<240/60=4>>4 hours
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