I need your help, I have a date that is variable, at that date you will add a frequency example 15 days , I would like from the date given example:
12 / 03/2018
make a count of your established frecuncia that therefore summary 15 days
and from that would throw the following date which would be:
03/27/2018 .
And in the same way I would like you to do another sum of other 15 days and so on.
NOTE: I am working with php and javaScript