Distribute specific amount to months

Hello everyone
I have specific amount (200) and I need UDF function that enables me to distribute this amount according to the following
For example:
If start date is 25 / 3 / 2016 (March) & End date is 3 / 7 / 2016 ( July)

So the number of days in March is 7 and the number of days in July is 3
and other months [April - May - June] are full days

Now I calculated the expected for the first month (March) with this formula

=(C3/(B3-A3))*(EOMONTH(A3,0)-A3+1)

and for the last month (July) with this formula

=(C3/(B3-A3))*DAY(B3)

As for the rest of full months : (200 - sum(the first month , the last month)) / the number of full months

Can it be done using UDF function which refers to Start date & End Date & The amount (Cost)
These are the three parameters

Hope it is clear
Thanks advanced for help