num ='s
#====================#    20

                              line | num spaces | num .'s | num spaces 
|        <><>        |         1   |     8      |    0    |     8
|      <>....<>      |         2   |     6      |    4    |     6
|    <>........<>    |         3   |     4      |    8    |     4
|  <>............<>  |         4   |     2      |    12   |     2
|<>................<>|         5   |     0      |    16   |     0
                        expression:  -2*line+10   4*line+4  -2*line+10

                              line | num spaces | num .'s | num spaces 
|<>................<>|         5   |     0      |    16   |     0
|  <>............<>  |         4   |     2      |    12   |     2
|    <>........<>    |         3   |     4      |    8    |     4
|      <>....<>      |         2   |     6      |    4    |     6
|        <><>        |         1   |     8      |    0    |     8
                        expression:  -2*line+10   4*line+4  -2*line+10

#====================# (same as first line)