Johnny's home is m miles from school. Johnny runs to school at a speed of 8 mph and then walks home from school at half that speed. How many hours longer does it take Johnny to walk home than to run to school?

Answer 1

The distance from Johnny's home to school is m miles.
To run to school, Johnny travels at a speed of 8 mph, so it takes him (m/8) hours to run to school.
To walk home, Johnny travels at half that speed, or 8 / 2 = <<8/2=4>>4 mph.
Thus, it takes Johnny (m/4) hours to walk home from school.
Therefore, Johnny takes (m/4) - (m/8) = (2m - m)/8 = m/8 hours longer to walk home than to run to school. Answer: \boxed{\frac{m}{8}}.