20. If we place Enid at the origin of
the coordinate system (where the x-axis is directed east, the y-axis
is directed north, and the unit is 1 mi), then the coordinates of
Tulsa will be (107; – 18). Norman's position can be obtained by
translation: 107 – 83 = 24; –18 – 63 = –81.

Answer: Norman is 24 mi east and 81 mi
south of Enid.

22. If the coordinates of P are (–2;
0), then the coordinates of P' are (–2 + 2; 0 + (–3)) = (0; –3).
The slope of the line PP' is m_{PP'} = (–3 – 0)/(0 –
(–2)) = –3/2. In the same way we may conclude that the slopes of
LL', AA', and TT' are also equal to –3/2, and these lines are
parallel.