Find last day month in a week.

[Berna11]

Good evening with the formula:

=DATE($A$1,1,1)+A3*7-1

I find in column D the date of the last day of the week number
of column B.
Now I would need that when you cross the month the date will stop
at the last day of that month.
As seen in the prospect the week N.5 ends on 04/02/2018 I would like
to have the date 31/01/2018 ....
the N. week 18 ends the 06/05/2018 would like to have 30/04/2018
Thank you

	A	B	C	D	E	F
1	2018
2		Num Week		date last day week	last day month
3		5		04/02/2018	31/01/2018
4		9		04/03/2018	28/02/2018
5		13		01/04/2018	31/03/2018
6		18		06/05/2018	30/04/2018
7
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[Special-K]

Given a date in D3

=EOMONTH(D3,-1)

will provide the last date of the previous month

[Berna11]

Thanks Special-K
but maybe I did not explain myself well.
During the month it's okay to give me the weekend day.
Only when going from one month to another would I have
the last day of the month current not of the week.

Example if I put N. week 23 is right to report
weekend 10/06/2018
while with your formula gives me 31/05/2018
I hope it's clear now.

[Berna11]

I solved by putting in column C
the first day of the week

=DATE($A$1,1,1)+A3*7-7

and in column E:

=IF(MONTH(C3)=MONTH(D3),D3,EOMONTH(C3,0))

	A	B	C	D	E	F
1	2018
2		Num Week	date first day week	date last day week	last day month
3		5	29/01/2018	04/02/2018	31/01/2018
4		9	26/02/2018	04/03/2018	28/02/2018
5		13	26/03/2018	01/04/2018	31/03/2018
6		18	30/04/2018	06/05/2018	30/04/2018
7