Count how many days in a column

[bluefeather8989]

I need a count of how many Mon there are in column D that have the number 1 in column K.
Example: In this picture there are 4 Mon in column D but only 3 have the number 1 in column K. cell R15 value is 3

 

[Phuoc]

Like this?

=COUNTIFS(D:D,"Mon",K:K,1)

 

[bluefeather8989]

Like this?

=COUNTIFS(D:D,"Mon",K:K,1)

I knew it was a countifs I just couldn't figure how to write it. . Thanks