I am trying to create a spread sheet that does several things

I have a start date [E1] and end date[F1], and between those dates I have a maximum number that can be reached over the total time [D1]. The start and end date are separated by calendar weeks, there is no max but should at least have 1 each week. I need to evenly distribute [D1]
For Example:
[E1] = 04/12/2015
[F1] = 9/19/2015
[D1] = 27

Manually have calculated the answer to be, how would I write a formula that would account for [E1][F1] AND [D1] changing? See image

Screenshot - 4_14_2015 , 12_21_44 PM.png