The last time Bob cut his hair he cut it to 6 inches.  His hair is now 36 inches long.  If hair grows at a rate of .5 inches per month how many years did it take him to grow out his hair?
His hair grew 36 inches - 6 inches = <<36-6=30>>30 inches
Hair grows at a rate of 12 months/year * 0.5 inches/month =<<12*0.5=6>>6 inches/year
It took him 30 inches / 6 inches/year = <<30/6=5>>5 years to grow his hair out.
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