title: Getting "TypeError: unsupported operand type(s) for -: 'list' and 'list'"
body: <p>Hi I know there are a few people that had this issue but none of the solutions I've seen are helping. I'm taking a set of data, reading the file then creating arrays from the data to input into this equation:
  <code>Dist = 10 ** ((app_m - abs_M + 5.) /5)</code>
  Where I app_m and abs_M are the arrays from the data.</p>
  
  <p>I'm using Python 2.7 and only just learning so if things can be explained as simply as possible that would be great </p>