In figure, if the length of ¯¯¯¯¯¯¯¯BC equals one-half the length of ¯¯¯¯¯¯¯¯AB, the sum of BC and CD equals three-fourth the length of ¯¯¯¯¯¯¯¯¯AD, and the length of ¯¯¯¯¯¯¯¯¯AD equals 16, calculate the distance between point C and the midpoint of ¯¯¯¯¯¯¯¯¯AD.